Permutation and Combinations

#import <cs50.h>
#import <stdio.h>
#import <string.h>
#import <stdlib.h>

int main (void)
{
    //Getting The Required Information
    long n = get_long ("Total Amount in a Set (n) : ");
    long r = get_long ("Amount in each Sub-Set (r) : ");


    long fac1 = 1;
    long fac2 = 1;
    long fac3 = 1;

    for (int i = 0; i < n; i++)
    {
        fac1 = fac1 * (n-i);
    }

    for (int j = 0; j < (n-r); j++)
    {
        fac2 = fac2 * ((n-r) - j);
    }

    for (int k = 0; k < r; k++)
    {
        fac3 = fac3 * (r-k);
    }


    long permutations = fac1/fac2;
    long combinations = permutations/fac3;

    printf("RESULT\n");
    printf("Permutations = %lo \n", permutations);
    printf("Combinations = %lo \n", combinations);


}