#include <iostream>
using namespace std;
long long f(int n)
{   
     if(n==19)
     return 121645100408832000;
     if(n<=1)
     return 1;
     return f(n-1)*n;
}
int main() {
    
    int n;
    cin >> n;
    long long factorial = 1;
    
    // write your code here......
    

    cout << f(n) << endl;
    
    return 0;
}