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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            int N;//人数
            int S;//必要な個数
            int i;
           //人数Nを入力
         N = int.Parse(Console.ReadLine());
         //必要な個数Sを求める
        //（合計を求めるアルゴリズム）
       S = 0;
       for (i=0;i<=N;i++)
 　　　{ S = S + 1; }//SをI増やす　S+=Iでもよい
            //Sを出力（表示）
            Console.WriteLine(S);
                //入力待ちに
             Console.ReadKey();
        }
    }
}