#include <bits/stdc++.h>
#define ll long long
#define endl "\n"
#define TranHungss(); ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
 
int main(){
    TranHungss();
    int n;
    scanf("%d", &n);
    long long sum = 0; // Lưu tổng các giai thừa
    for(int i = 1; i <= n; i++){
        long long giai_thua = 1; // Mỗi vòng lặp khởi tạo lại biến giai thừa
        for(int j = 1; j <= i; j++){
            giai_thua *= (long long)j; // Nhân j vào giai thừa j chạy từ 1 -> i
        }
        sum += giai_thua; // Sau khi tính xong giai thừa cộng vào biến sum
    }
    printf("%lld", sum);
}

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