#include<bits/stdc++.h>
 
using namespace std;
 
#define rep(i, n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define pb push_back
#define int long long

signed main(){
    int n;
    cin>>n;
    int ans=1;

    for(int i=1;i<=n;i++){
        ans*=i;
    }
    cout<<ans<<endl;
}