/* Returns if year is a leap year 
   Input: A legal year - a non-negative integer.
   Output: Whether year is a leap year. An integer interpreted as a boolean value.
*/

int isLeapYear(int year){
  int res;
  if (year % 400 == 0)
    res = 1;
  else if (year % 100 == 0)
    res = 0;
  else if (year % 4 == 0)
    res = 1;
  else res = 0;
  return res;
}