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 Scala (2.11.7) (judge verdict: Accepted)

import java.security.KeyStore.TrustedCertificateEntry

object Main {

  import java.util.Scanner

  def main(args: Array[String]): Unit = {
    val scanner = new Scanner(System.in)
    val s = scanner.next
    var n = s.toInt
    var sum = 0

    while(n != 0){
      sum += n
      n -= 1
    }

    println(sum)
  }
}