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#include <stdio.h>

int main(void)
{
    int value = 1, leap_year = 0;

    /* keep looping forever */
    while (value > 0)
    {
        printf ("Enter a year: ");
        /* year is a float value */
        scanf("%d", &value);
        fflush(stdin);
        
        if ((value % 4) != 0)
        {
            /* value was not divisible by 4  */
            leap_year = 0;
        }
        /* year is divisible by four and last two digits are not 00 */
        else if ((value % 4 == 0) && (value % 100 != 0))
        {
            leap_year = 1;
        }
        /* last two digits are 00 and the value is evenly divisible
         * by 4 */
        else if ((value % 100 == 0) && (value % 400 == 0))
        {
            leap_year = 1;
        }
        else
            leap_year = 0;

        if (value > 0)
        {
            if (leap_year == 1)
                printf("%d is a leap year!\n", value);
            else 
                printf("%d is not a leap year!\n", value);
        }
    }
}