#include<iostream>
using namespace std;
int factorial(int x){递归算阶乘
return x==1?1:x*factorial(x-1);
}
int main()
{
int n;
cin>>n;
int sum=0;
for(int i=1;i<=n;i++)
sum+=factorial(i);
cout<<sum;
return 0;
}
#include<iostream>
using namespace std;
int factorial(int x){递归算阶乘
return x==1?1:x*factorial(x-1);
}
int main()
{
int n;
cin>>n;
int sum=0;
for(int i=1;i<=n;i++)
sum+=factorial(i);
cout<<sum;
return 0;
}