HDU-1001Sum Problem

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

1 100

 

Sample Output

1 5050

 

ac代码：

#include<stdio.h>
main()
{ signed __int64 n,sum=0,i;
    while(scanf("%I64d",&n)!=EOF)
    {
        for(i=1;i<=n;i++)
        {
            sum+=i;
        }
        printf("%I64d\n\n",sum);
        sum=0;
    }
}