改AC就关注

记录

#include <bits/stdc++.h>
using namespace std;
void print(__int128 x){
    if (x < 0){
        putchar('-');
        x = -x;
    }
    if (x > 9) print(x / 10);
    putchar(x % 10 + '0');
}
__int128 read(){
    __int128 x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9'){
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9'){
        x = x * 10 + ch - '0';
        ch = getchar();
    }
    return x * f;
}
__int128 jiecheng(__int128 shu){
    __int128 sum = 1;
    for(__int128 i = 2; i <= shu; i++){
        sum *= i;
    }
    return sum;
}

int main(){
    __int128 a, sum = 0;
    a = read();
    for(__int128 i = 1; i <= a; i++){
        sum += jiecheng(i);
    }
    
    print(sum);
    return 0;
}