#include<bits/stdc++.h> using namespace std; int main() { int n,i,j,ans=0,sum=1; cin>>n; for(i=1;i<=n;i=i+1) { for(j=1;j<=i;j=j+1) { sum=sum*j; } ans=sum+ans; sum=1;} cout<<ans; return 0; }