#include <bits/stdc++.h>

using namespace std;

int main() {
    int n;
    cin >> n; // n!+(n-1)!+(n-2)!+...+1!

    int sum = 0;                   //结果，累加和
    for (int i = n; i >= 1; i--) { //枚举 n,n-1,n-2,....,1
        //计算n这个数字的阶乘
        int res = 1;
        for (int j = i; j >= 1; j--) res *= j;
        sum += res;
    }
    cout << sum << endl;
    return 0;
}