diff --git a/2021/day05_vents.py b/2021/day05_vents.py
new file mode 100644
index 0000000..3a2dbdf
--- /dev/null
+++ b/2021/day05_vents.py
@@ -0,0 +1,82 @@
+from dataclasses import dataclass
+from typing import List, Set
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        data = f.read().strip().split("\n")
+
+    data = parse_data(data)
+    solution_part_1 = solve_part_1(data)
+
+    print(f"1. Found {solution_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == solution_part_1
+
+    solution_part_2 = solve_part_2(data)
+    print(f"2. Found {solution_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == solution_part_2
+
+
+@dataclass(frozen=True)
+class Point:
+    x: int
+    y: int
+
+
+@dataclass(frozen=True)
+class Segment:
+    start: Point
+    end: Point
+
+    def is_horizontal(self):
+        return self.start.y == self.end.y
+
+    def is_vertical(self):
+        return self.start.x == self.end.x
+
+    def get_points(self) -> Set[Point]:
+        if self.is_horizontal():
+            start = min(self.start.x, self.end.x)
+            end = max(self.start.x, self.end.x)
+            return {Point(x, self.start.y) for x in range(start, end + 1)}
+        elif self.is_vertical():
+            start = min(self.start.y, self.end.y)
+            end = max(self.start.y, self.end.y)
+            return {Point(self.start.x, y) for y in range(start, end + 1)}
+        return set()
+
+
+def parse_data(data: List[str]) -> List[Segment]:
+    segments = []
+    for line in data:
+        start, end = line.split(" -> ")
+        start = start.split(",")
+        end = end.split(",")
+        start = Point(int(start[0]), int(start[1]))
+        end = Point(int(end[0]), int(end[1]))
+        segment = Segment(start, end)
+        segments.append(segment)
+    return segments
+
+
+def solve_part_1(data: List[Segment]) -> int:
+    seen_points = set()
+    multiple_times = set()
+    for segment in data:
+        for point in segment.get_points():
+            if point in seen_points:
+                multiple_times.add(point)
+            seen_points.add(point)
+    return len(multiple_times)
+
+
+def solve_part_2(data: List[Segment]) -> int:
+    return 0
+
+
+if __name__ == "__main__":
+    main("inputs/day05-test1", expected_part_1=5)
+    main("inputs/day05", expected_part_1=7297)
diff --git a/2021/inputs/day05 b/2021/inputs/day05
new file mode 100644
index 0000000..abe5fe3
--- /dev/null
+++ b/2021/inputs/day05
@@ -0,0 +1,500 @@
+427,523 -> 427,790
+94,639 -> 94,951
+757,371 -> 465,663
+503,935 -> 503,148
+655,565 -> 655,951
+167,754 -> 710,211
+634,433 -> 245,433
+449,889 -> 449,509
+152,753 -> 207,808
+301,90 -> 301,982
+566,405 -> 482,405
+758,741 -> 847,652
+342,686 -> 921,107
+741,317 -> 741,533
+976,917 -> 976,664
+273,272 -> 273,899
+326,616 -> 326,478
+483,906 -> 391,814
+20,165 -> 20,349
+860,533 -> 860,137
+846,834 -> 846,610
+155,923 -> 241,923
+989,984 -> 17,12
+711,681 -> 82,52
+312,788 -> 312,281
+319,746 -> 892,746
+568,555 -> 757,555
+659,450 -> 940,450
+870,260 -> 870,487
+110,794 -> 604,794
+509,141 -> 509,99
+29,68 -> 29,713
+340,688 -> 820,688
+428,46 -> 902,520
+539,525 -> 539,210
+181,822 -> 806,822
+551,338 -> 551,79
+894,542 -> 894,151
+700,625 -> 700,60
+143,736 -> 143,770
+810,975 -> 54,219
+44,373 -> 44,514
+849,794 -> 120,794
+347,690 -> 97,440
+10,625 -> 57,625
+541,202 -> 799,202
+375,491 -> 809,925
+271,474 -> 271,905
+980,825 -> 980,908
+600,751 -> 624,751
+120,978 -> 958,140
+262,916 -> 262,794
+399,350 -> 399,666
+623,270 -> 158,735
+585,792 -> 585,381
+168,34 -> 168,88
+256,806 -> 566,806
+196,397 -> 326,397
+583,677 -> 172,677
+45,242 -> 311,508
+530,469 -> 433,566
+46,101 -> 877,932
+607,655 -> 485,777
+773,672 -> 461,360
+340,30 -> 659,30
+846,952 -> 846,917
+457,700 -> 125,368
+571,656 -> 561,656
+251,30 -> 576,30
+79,197 -> 79,87
+518,51 -> 518,904
+916,802 -> 181,67
+23,626 -> 485,626
+956,106 -> 956,811
+849,384 -> 743,278
+893,153 -> 893,608
+17,989 -> 933,73
+701,119 -> 701,704
+494,580 -> 494,821
+605,740 -> 605,363
+823,58 -> 823,166
+250,363 -> 566,363
+418,178 -> 783,178
+273,82 -> 273,115
+545,489 -> 656,489
+468,671 -> 966,671
+376,744 -> 178,942
+62,728 -> 589,201
+588,150 -> 467,29
+202,664 -> 751,115
+519,547 -> 916,150
+803,483 -> 380,60
+599,459 -> 922,459
+162,680 -> 162,385
+823,94 -> 18,899
+802,734 -> 415,347
+115,964 -> 115,935
+749,595 -> 749,770
+229,64 -> 582,64
+103,496 -> 551,48
+137,581 -> 707,11
+501,563 -> 895,957
+59,222 -> 620,222
+874,249 -> 874,938
+201,927 -> 927,201
+630,619 -> 655,619
+666,331 -> 413,78
+517,650 -> 425,558
+803,256 -> 803,598
+303,460 -> 606,763
+124,975 -> 967,132
+867,528 -> 867,363
+239,140 -> 239,211
+975,779 -> 364,168
+971,49 -> 531,49
+408,932 -> 143,932
+927,663 -> 392,128
+497,246 -> 497,389
+849,935 -> 15,101
+582,517 -> 543,517
+410,85 -> 237,85
+292,316 -> 841,316
+753,708 -> 753,38
+266,328 -> 267,327
+789,980 -> 16,207
+514,963 -> 514,180
+865,532 -> 687,710
+544,620 -> 956,208
+132,287 -> 557,287
+268,710 -> 268,684
+234,746 -> 234,688
+51,906 -> 51,911
+191,159 -> 428,159
+834,956 -> 834,565
+916,242 -> 230,928
+227,789 -> 227,689
+206,767 -> 705,268
+291,403 -> 578,403
+35,890 -> 956,890
+185,618 -> 402,401
+989,858 -> 284,858
+391,284 -> 391,74
+717,158 -> 670,111
+188,146 -> 785,743
+602,696 -> 602,367
+975,972 -> 975,317
+146,301 -> 146,205
+328,215 -> 861,215
+15,653 -> 990,653
+48,101 -> 48,34
+929,547 -> 506,970
+901,519 -> 670,519
+801,560 -> 19,560
+953,829 -> 876,829
+856,317 -> 856,787
+618,171 -> 86,703
+823,622 -> 369,168
+209,291 -> 846,928
+944,601 -> 944,544
+678,223 -> 987,223
+893,143 -> 54,982
+30,740 -> 244,740
+974,974 -> 15,15
+497,557 -> 63,557
+846,193 -> 846,964
+83,119 -> 946,982
+864,179 -> 864,387
+583,312 -> 77,818
+612,154 -> 612,641
+487,136 -> 487,938
+502,611 -> 215,898
+648,978 -> 648,885
+373,372 -> 318,372
+582,988 -> 168,574
+453,261 -> 899,261
+467,578 -> 33,578
+876,138 -> 683,331
+708,248 -> 132,824
+686,56 -> 686,211
+687,964 -> 687,485
+626,76 -> 626,222
+630,176 -> 630,485
+968,608 -> 968,382
+943,69 -> 943,856
+173,344 -> 173,902
+193,918 -> 326,918
+811,748 -> 379,316
+484,941 -> 113,570
+277,635 -> 156,514
+770,573 -> 691,573
+37,475 -> 464,475
+720,856 -> 676,856
+988,13 -> 25,976
+414,74 -> 140,74
+169,158 -> 29,298
+611,910 -> 611,718
+851,161 -> 507,161
+76,969 -> 76,114
+270,243 -> 976,949
+375,607 -> 325,657
+738,450 -> 196,450
+153,776 -> 153,325
+862,123 -> 862,535
+705,933 -> 931,933
+900,26 -> 35,891
+870,66 -> 79,857
+815,569 -> 347,569
+950,290 -> 757,290
+719,446 -> 317,848
+243,531 -> 671,531
+320,807 -> 380,807
+221,984 -> 221,858
+832,308 -> 832,950
+522,694 -> 584,694
+412,48 -> 412,328
+898,690 -> 646,690
+602,191 -> 106,191
+58,961 -> 58,879
+177,413 -> 147,383
+48,159 -> 48,639
+18,935 -> 883,70
+26,68 -> 406,68
+579,73 -> 579,523
+975,825 -> 975,737
+390,125 -> 737,472
+127,179 -> 127,111
+506,557 -> 576,487
+161,210 -> 324,47
+524,165 -> 524,67
+938,790 -> 184,36
+302,431 -> 548,677
+559,363 -> 559,913
+936,10 -> 176,770
+828,976 -> 657,976
+864,14 -> 864,607
+28,46 -> 28,347
+732,742 -> 732,615
+91,712 -> 91,279
+982,884 -> 772,674
+917,47 -> 683,47
+631,697 -> 83,697
+463,413 -> 463,949
+719,348 -> 197,870
+980,25 -> 24,981
+64,608 -> 410,954
+103,882 -> 103,842
+279,10 -> 830,561
+409,573 -> 409,247
+673,291 -> 222,291
+315,143 -> 942,770
+216,89 -> 80,225
+134,936 -> 967,103
+387,566 -> 82,566
+282,259 -> 862,839
+930,225 -> 930,775
+460,370 -> 460,922
+276,254 -> 518,496
+647,881 -> 293,527
+983,977 -> 90,84
+336,836 -> 336,392
+96,888 -> 963,21
+42,47 -> 978,983
+923,280 -> 726,83
+311,486 -> 505,292
+496,637 -> 861,637
+575,438 -> 575,498
+228,754 -> 228,599
+965,963 -> 21,19
+834,171 -> 730,171
+497,234 -> 497,448
+977,970 -> 977,618
+335,422 -> 335,640
+931,954 -> 36,59
+140,966 -> 871,235
+352,88 -> 449,88
+631,332 -> 735,332
+765,823 -> 48,106
+496,685 -> 103,685
+89,416 -> 89,37
+121,544 -> 569,544
+643,712 -> 596,712
+662,656 -> 739,656
+42,386 -> 42,697
+959,875 -> 959,527
+874,967 -> 120,213
+962,649 -> 240,649
+627,714 -> 266,714
+148,301 -> 148,383
+883,491 -> 883,605
+242,401 -> 348,401
+660,931 -> 420,931
+475,72 -> 955,552
+912,949 -> 912,881
+928,330 -> 45,330
+474,203 -> 131,203
+805,459 -> 818,459
+534,645 -> 639,750
+68,911 -> 933,46
+717,276 -> 21,972
+233,615 -> 957,615
+902,495 -> 902,867
+230,427 -> 230,421
+630,917 -> 845,917
+884,903 -> 34,53
+157,205 -> 157,409
+857,588 -> 608,588
+422,863 -> 422,469
+890,83 -> 722,251
+546,318 -> 138,726
+691,881 -> 52,242
+171,435 -> 209,435
+978,15 -> 702,15
+581,86 -> 581,282
+61,767 -> 61,903
+835,289 -> 835,941
+176,351 -> 707,882
+571,84 -> 571,788
+700,373 -> 700,650
+40,40 -> 945,945
+82,616 -> 809,616
+351,402 -> 455,402
+517,242 -> 73,686
+489,795 -> 814,795
+543,734 -> 611,734
+688,849 -> 688,571
+631,903 -> 883,903
+312,636 -> 667,281
+213,575 -> 699,89
+752,128 -> 161,719
+754,931 -> 754,474
+748,666 -> 748,54
+123,667 -> 57,667
+140,497 -> 140,644
+634,961 -> 187,514
+822,865 -> 822,126
+58,162 -> 632,736
+417,164 -> 166,164
+943,597 -> 943,274
+355,756 -> 355,167
+340,546 -> 232,438
+166,125 -> 166,96
+354,394 -> 354,579
+147,844 -> 155,844
+652,723 -> 719,656
+584,582 -> 667,665
+514,373 -> 685,202
+308,404 -> 966,404
+124,179 -> 916,971
+706,597 -> 455,597
+52,822 -> 510,364
+419,900 -> 860,900
+153,649 -> 872,649
+915,160 -> 56,160
+422,346 -> 422,38
+940,73 -> 940,784
+922,581 -> 922,753
+949,821 -> 949,621
+591,778 -> 145,778
+93,685 -> 164,756
+287,469 -> 287,948
+953,952 -> 446,445
+935,47 -> 12,970
+458,109 -> 458,639
+71,643 -> 644,70
+812,214 -> 812,655
+488,496 -> 158,496
+113,868 -> 755,226
+666,429 -> 666,920
+962,246 -> 517,246
+400,261 -> 400,713
+601,617 -> 943,275
+904,847 -> 120,63
+556,334 -> 278,612
+416,463 -> 59,463
+724,401 -> 871,548
+701,210 -> 426,485
+786,116 -> 786,904
+976,979 -> 157,160
+674,377 -> 674,891
+321,829 -> 891,829
+404,84 -> 404,800
+975,850 -> 906,781
+753,331 -> 978,331
+87,240 -> 87,383
+167,390 -> 167,20
+258,931 -> 107,780
+672,313 -> 696,313
+589,88 -> 589,13
+637,65 -> 637,808
+532,610 -> 532,756
+612,482 -> 318,482
+522,322 -> 135,322
+89,49 -> 89,679
+475,506 -> 475,973
+385,348 -> 229,348
+633,978 -> 633,255
+978,833 -> 978,436
+746,553 -> 707,553
+970,820 -> 970,548
+589,59 -> 589,19
+674,890 -> 16,890
+838,315 -> 413,740
+39,129 -> 860,950
+923,755 -> 425,257
+757,929 -> 940,746
+639,390 -> 104,925
+650,512 -> 260,902
+718,90 -> 987,90
+352,228 -> 795,671
+141,629 -> 491,279
+755,616 -> 368,616
+117,113 -> 707,703
+206,73 -> 926,793
+372,415 -> 372,130
+894,632 -> 611,632
+974,554 -> 878,554
+823,710 -> 823,972
+730,711 -> 582,859
+94,912 -> 108,912
+782,190 -> 88,884
+668,567 -> 336,567
+87,266 -> 327,506
+738,303 -> 36,303
+320,358 -> 445,358
+566,725 -> 695,725
+94,364 -> 94,64
+884,184 -> 159,909
+947,575 -> 947,662
+658,741 -> 658,470
+512,776 -> 512,960
+96,757 -> 950,757
+349,604 -> 349,760
+459,247 -> 355,143
+90,12 -> 95,12
+28,27 -> 981,980
+388,959 -> 508,959
+704,194 -> 148,194
+349,546 -> 349,259
+30,38 -> 720,728
+307,631 -> 307,282
+520,417 -> 154,417
+746,771 -> 924,771
+838,932 -> 20,114
+406,141 -> 406,75
+15,35 -> 963,983
+264,143 -> 948,827
+545,899 -> 742,899
+759,356 -> 309,356
+686,707 -> 224,245
+226,985 -> 962,249
+826,628 -> 826,637
+985,329 -> 683,631
+586,283 -> 586,258
+602,703 -> 243,703
+419,883 -> 419,556
+475,375 -> 211,111
+981,15 -> 19,977
+989,10 -> 10,989
+238,350 -> 479,591
+720,714 -> 603,714
+969,985 -> 35,51
+844,356 -> 837,349
+450,354 -> 450,834
+385,870 -> 385,758
+911,856 -> 89,34
+948,124 -> 989,124
+439,556 -> 439,310
+990,233 -> 990,633
+747,723 -> 943,527
+418,23 -> 804,23
+876,96 -> 38,934
+556,92 -> 532,92
+727,155 -> 727,279
+674,545 -> 940,811
+118,879 -> 420,879
+141,50 -> 426,335
+591,180 -> 591,537
+662,511 -> 681,511
+776,858 -> 776,956
+872,329 -> 87,329
+183,985 -> 114,985
+186,179 -> 186,801
+354,933 -> 491,933
+10,223 -> 759,972
+112,626 -> 702,36
+498,78 -> 161,78
+196,61 -> 814,679
+629,71 -> 116,71
+23,281 -> 23,32
+819,810 -> 432,423
+187,276 -> 187,912
+95,683 -> 576,683
+125,813 -> 856,82
+98,882 -> 140,882
+843,909 -> 198,909
+192,904 -> 192,335
+375,342 -> 375,668
+61,804 -> 61,832
+475,387 -> 966,878
+822,740 -> 822,186
diff --git a/2021/inputs/day05-test1 b/2021/inputs/day05-test1
new file mode 100644
index 0000000..1d4e36d
--- /dev/null
+++ b/2021/inputs/day05-test1
@@ -0,0 +1,10 @@
+0,9 -> 5,9
+8,0 -> 0,8
+9,4 -> 3,4
+2,2 -> 2,1
+7,0 -> 7,4
+6,4 -> 2,0
+0,9 -> 2,9
+3,4 -> 1,4
+0,0 -> 8,8
+5,5 -> 8,2
\ No newline at end of file