Dev - C++ - problema de combinaciones

#include <iostream>

long long int factorial(int n);

int main()

{

    int n, r;

    std::cout << "Valor de N: "; std::cin >> n;

    std::cout << "Valor de R: "; std::cin >> r;

    r = r <= n  ? r : n;

    std::cout << "\nCombinaciones posibles: " << factorial(n) / (factorial(r) * factorial(n - r)) << std::endl;

    return 0;

}

long long int factorial(int n)

{

    long long int fact = 1;

    for (int i = 1; i <= n; i++)

        fact *= i;

    return fact;

}