In 2001, month number 1 had 31 days.
In 2001, month number 2 had 28 days.
In 2001, month number 3 had 31 days.
In 2001, month number 4 had 30 days.
In 2001, month number 5 had 31 days.
In 2001, month number 6 had 30 days.
In 2001, month number 7 had 31 days.
In 2001, month number 8 had 31 days.
In 2001, month number 9 had 30 days.
In 2001, month number 10 had 31 days.
In 2001, month number 11 had 30 days.
In 2001, month number 12 had 31 days.
daysInMonth(2,2000) = 29
daysInMonth(2,2001) = 28
daysInMonth(2,2002) = 28
daysInMonth(2,2003) = 28
daysInMonth(2,2004) = 29