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

1

100

Sample Output

1

5050

#include<stdio.h>

#include<stdlib.h>

int main()

{

    int n,sum;

    while(scanf("%d",&n)!=EOF)//多次输入

    {

        sum=0;//放入循环体内，保证每次sum都被清0

        while(n)//当n！=0时，执行循环

        {

            sum+=n;//累加

            n=n-1;

        }

        printf("%d\n\n",sum);//输出结果

    }

return 0;

}