Problem:
Score : 100 points

Problem Statement

There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N-th child. How many candies will be necessary in total?

Constraints

1≦N≦100

Input

The input is given from Standard Input in the following format:

N

Output

Print the necessary number of candies in total.

Sample Input 1

3

Sample Output 1

6

The answer is 1+2+3=6.

Sample Input 2

10

Sample Output 2

55

The sum of the integers from 1 to 10 is 55.

Sample Input 3

1

Sample Output 3

1

Only one child. The answer is 1 in this case.

Solution in JavaScript (node.js v5.12) (judge verdict: Runtime Error)

function Main(input) {
    // 1行目がinput[0], 2行目がinput[1], …に入る
    input = input.split("\n");
    //tmp = input[1].split(" ");
    //文字列から10進数に変換するときはparseIntを使います
    /*
    var a = parseInt(input[0], 10);
    var b = parseInt(tmp[0], 10);
    var c = parseInt(tmp[1], 10);
    var s = input[2];
    */
    var a = parseInt(input[0], 10);
    let count = 0;
   for(let i = 0; i<=a; i++){
       count += i;
   }
    //出力
    //console.log('%d %s', a + b + c, s);
    console.log(""+count);
}