#include stdio.h

int main() {
    int year = 2024;
    int sundays = 0;
    for (int month = 1; month = 12; month++) {
        int days = 31;
        if (month == 4 || month == 6 || month == 9 || month == 11) {
            days = 30;
        } else if (month == 2) {
            if (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)) {
                days = 29;
            } else {
                days = 28;
            }
        }
        for (int day = 1; day = days; day++) {
            if ((year - 1) % 4 == 0 && ((year - 1) % 100 != 0 || (year - 1) % 400 == 0)) {
                int day_of_week = (365 + ((year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400) + (31 * (month - 1)) - ((month  2) ? (4 * month + 23) / 10 : 0) + day) % 7;
                if (day_of_week == 0) {
                    sundays++;
                }
            } else {
                int day_of_week = (365 + ((year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400) + (31 * (month - 1)) - ((month  2) ? (4 * month + 23) / 10 : 0) + day + 1) % 7;
                if (day_of_week == 0) {
                    sundays++;
                }
            }
        }
    }
    printf("There are %d Sundays in %d (a leap year).\n", sundays, year);
    return 0;
}

    
    

Guess the output?