1+2+3+......+n

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<stdio.h>int main(){    int i,n,sum;    while(scanf("%d",&n)!=EOF)    {        sum=0;        for(i=1;i<=n;i++)        sum+=i;        printf("%d\n",sum);        printf("\n");    }    return 0;}