きったんの頭_ん中☆

#! /usr/bin/env python3
"""
pe19.py
https://mind.kittttttan.info/py/pe19
"""

from datetime import date

def pe19(n=2000):
    """
    How many Sundays fell on the first of the month
    during the twentieth century?
    """
    s = 0
    for y in range(1901, n + 1):
        for m in range(1, 13):
            d = date(y, m, 1)
            if d.weekday() == 6:
                s += 1
    print(s)

if __name__ == "__main__":
    pe19()