Weekdays

#include <iostream>

const int offset[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};

const std::string daynames[] = {
  "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};

int main () {
  int day, month, year;
  std::cin >> day >> month >> year;
  year -= month < 3;
  int weekday = (year + year/4 - year/100 + year/400 + offset[month-1] + day) % 7;

  std::cout << "Day: " << daynames[weekday];
  return 0;
}