You are given the following information, but you may prefer to do some research for yourself.
- 1 Jan 1900 was a Monday.
- Thirty days has September,
April, June, and November.
All the rest have thirty-one,
Saving February alone,
Which has twenty-eight, rain, or shine?
And on leap years, twenty-nine.
- A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?
This is a Project Euler Problem: https://projecteuler.net/problem=19