#include <stdio.h>

long factorial(int value);
int combination(int n, int r);
int permutation(int n, int r);

void main() {
    int resultOfCombination = combination(5, 2);
    int resultOfPermutation = permutation(5, 2);

    printf("Combination: %d\n", resultOfCombination);
    printf("Permutation: %d\n", resultOfPermutation);
}

long factorial(int value) {
    int total = 1;
    for (; value >= 1; value--)
        total *= value;

    return total;
}

int combination(int n, int r) {
    return factorial(n) / (factorial(r) * factorial(n - r));
}

int permutation(int n, int r) {
    return factorial(n) / factorial(n - r);
}