1100：金币

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
int i=1,s=0,sum=0,n;
scanf("%d",&n);
while(s<n)
{
s=s+i;
sum=sum+i*i;
i++;
}
sum=sum-(s-n)*(i-1);
printf("%d",sum);
return 0;
}100'