1014

 1 #include <iostream>

 2 using namespace std;

 3 int main()

 4 {long long s=0,t=1;

 5 int m,n;

 6   cin>>n;

 7   for (m=1;m<=n;m++)

 8   {

 9    t=t*m;

10    s=s+t;

11   }

12   cout<<s<<endl;

13   return 0;

14  }