Вариант 14. Факториал

#include <stdio.h>

unsigned long long int factorial(int n) {
  return (n < 2) ? 1 : n * factorial (n - 1);
}

int main() {
    unsigned int m, n;
    scanf("%u%u", &m, &n);
    printf("%lf", (factorial(m) + factorial(n)) * 1.0 / factorial(m + n));
}