Leap Year Problem

if (year is not divisible by 4) then (it is a common year) else if (year is not divisible by 100) then (it is a leap year) else if (year is not divisible by 400) then (it is a common year) else (it is a leap year)

http://en.wikipedia.org/wiki/Leap_year

The all given number is divisible by four, so we should reject one.

Leap year rule 1: if the year is divisible by 4, then it is a leap year.

Leap year rule 2: if the year is divisible by 100, then it is not a leap year.

Leap year rule 3: if the year is divisible by 400, then it is a leap year.

So, leap year : $0, 4, 8, 12, \cdots, 96, \color{#D61F06} \cancel { 100 }$ $,104,$ $108, 112, 116, \cdots, 392, 396,$ $\color{#3D99F6}400$ $,404, 408, 412, \cdots, 1888, 1892, 1896, 1904, 1908, \cdots, 1992, 1996,$ $\color{#3D99F6} 2000$ $,2004, 2008, 2012, 2016, 2020, 2024, \cdots$ .