Problem Description

In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + ... + n.

Input

The input will consist of a series of integers n, one integer per line.

Output

For each case, output SUM(n) in one line, followed by a blank line. You may assume the result will be in the range of 32-bit signed integer.

Sample Input

1
100

Sample Output

1

5050

这么简单？我是不是没读懂题目啊？

那数据大小呢 ？

#include<iostream.h>
void main()
{
int n,temp,sum;
cout<<"请输入一个整数n:";
cin>>n>>endl;
for(temp=n;temp<=n;temp++)
{
sum+=temp;
}
cout<<sum<<endl;
}

int sum()
{
cout<<"Please input a series of integers(end with 0).\n";
int i,sum=0;
while(cin>>i,i!=0)
sum+=i;
return sum;
}