diff --git a/python/oct3/level0/date.py b/python/oct3/level0/date.py
new file mode 100644
index 0000000..c121556
--- /dev/null
+++ b/python/oct3/level0/date.py
@@ -0,0 +1,24 @@
+def is_leap_year(yyyy: int) -> bool:
+    return not (yyyy % 4 or (yyyy % 400 and not yyyy % 100))
+
+
+
+def sum_months(mm: int, yyyy: int) -> int:
+    months = [31, 29 if is_leap_year(yyyy) else 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+    return sum(months[:mm])
+
+
+def nth_day(s: str) -> int:
+    """Calculate the nth day since the beginning of the year."""
+    mm, dd, yyyy = map(int, [s[:2], s[2:4], s[4:]])
+    day_since_new_year = dd + sum_months(mm-1, yyyy)
+    return yyyy*1000 + day_since_new_year
+
+
+print("we're testing the nth day function...", end='')
+assert(nth_day("02072016") == 2016038)
+assert(nth_day("12201996") == 1996355)
+# assert(nth_day("abcdef") == None)
+assert(nth_day("12312020") == 2020366)
+assert(nth_day("12312021") == 2021365)
+print("and it passes the example cases")