#include <iostream>
using namespace std;

long long mul = 1;

long long dfs(int n)
{
    if(n == 1) return 1;
    mul=n*dfs(n-1);
    return mul;
}

int main() {
    
    int n;
    cin >> n;
    long long factorial = 1;
    
    // write your code here......
    long long ref = dfs(n);
    factorial = ref;
    cout << factorial << endl;
    
    return 0;
}