杭電oj1001

Problem Description

Hey, welcome to HDOJ(Hangzhou Dianzi University Online Judge).

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

1100

 

Sample Output

15050

#include<iostream>
using namespace std;

int main(){
	int i,sum,n;
	while(cin>>n){		//重複輸入 
		sum=0;
		for(i=0;i<=n;i++)
			sum+=i;
		cout<<sum<<"\n\n";
	}
	return 0;
}