#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int sumf(int n) { int sum = 1; for (int i = 1; i <= n; i++) { sum *= i; } return sum; } int main(){ int n; cin >> n; int sum = 0; for (int i = 1; i <= n; i++) { sum += sumf(i); } cout << sum; return 0; }