Sum

Time Limit: 1 sec

 

The Problem

Make a simple program that reads one variable named N, Your task is to find the sum of all integer numbers lying between 1 and N inclusive.

 

The Input

Input file consist of several lines. Each line contains an integer N which is not greater than 100 by its absolute value.

 

The Output

For each line of input, write a single integer number that is the sum of all integer numbers lying between 1 and N inclusive. Each output should be in separate line.

 

Sample Input

5

-3

 

Sample Output

15

-5

 

 

 

 

Problem Setter: Shahin ShamS