#include<bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);i++)
#define loop(i,x,n) for(int i=(x);i<(n);i++)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mp make_pair
#define fir first
#define sec second
#define ub upper_bound
#define lb lower_bound
#define int long long
using namespace std;
const int MOD=1000000007;
const int INF=1000000009;

int memo[30];

int fac(int m){
  if(m==1)return 1;
  return m*fac(m-1);
}

signed main(){
  int n;
  cin>>n;
  cout<<fac(n)<<endl;
  return 0;
}