Turkish Project Euler Question 19 The Number of Sundays

January 1, 1900, was a Monday.
September, April, June, and November have 30 days, other months have 31 days. February, unlike the other months, has 28 days and 29 days in leap years.
Years divisible by 4 are leap years, but centuries are not leap years unless divisible by 400.

In the 20th century (between January 1, 1901 and December 31, 2000), how many times did Sunday fall on the first day of any month?

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