Professor’s Homework

Time Limit: 1 sec

 

The Problem

Nora is learning summation of numbers. So her Professor has given her homework   “Summation of numbers from 1 to N”. Can you help Nora to complete her homework?

 

1 + 2 + 3 + … + N = ???

 

 

The Input

The input file contains 1 integer number N (N<=200).

 

The Output

Output will show the sum of series 1 to N numbers in a separate line.

 

Sample Input

125 

 

Sample Output

 7875

 

 

 

 

Problem Setter: Shahin ShamS

Special thanks to Samia Safa Ahmed