MultiFactorial

#include <iostream>
using namespace std;
int main()
{
    int n;
    int nn = 1;
    int i = 0;
    cin >> n;
    if (n % 2 == 0) {
         i = 2;
    }
    else {
        i = 1;
    }
    while (nn < n) {
        nn = nn * i;
        i += 2;
    }
    cout << nn << endl;
}