1 files changed, 6 insertions, 0 deletions
diff --git a/utils.py b/utils.py
index d322ed0..91b90ff 100644
--- a/utils.py
+++ b/utils.py
@@ -1,6 +1,7 @@
 from collections import deque
 from collections.abc import Iterable, Iterator, Generator
 from itertools import islice
+from sys import argv
 from typing import TypeVar
 
 T = TypeVar('T')
@@ -13,3 +14,8 @@ def sliding_window(iterable: Iterable[T], n: int) -> Generator[tuple[T, ...], No
     for x in it:
         window.append(x)
         yield tuple(window)
+
+def open_day(n: int):
+    if len(argv) == 2:
+        return open(argv[1])
+    return open(f'{n}.in')