代码

#include<bits/stdc++.h>
using namespace std;

int main()
{
int n;//总天数
cin >> n;
int day = 1;//天数
//int money = 0;//每天获得的钱数
int sum = 0;//总和

while(n >= day)
    {
        sum += day * day;
        n -= day;
        day++;
    }
//cout << day << " " << n << endl;
sum = sum + day * n;
cout << sum;

}