HDU1001——Sum 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

#include<stdio.h>
int num(int n)
{
	int sum=n;
	while(n--)
	{
		sum=sum+n;
	}
	return sum;
}
int main()
{
	int i;
	while(~scanf("%d",&i))
	{
		printf("%d\n",num(i));
		printf("\n");
	}
	return 0;
	
}