#include<iostream>
#define rep(i,s,n)for(int i=s;i<n;i++)
using namespace std;
using ll=long long;
int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n,i;
  ll sum;
  cin >> n;
  sum=1;
  rep(i,1,n+1)sum*=i;
  cout << sum <<endl;
  return 0;
}

