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# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.ComponentModel.DataAnnotations;
using System.Globalization;
using System.IO.Pipes;
using System.Runtime.InteropServices;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            int x;
            x = int.Parse(Console.ReadLine());
            Console.WriteLine((x+1)*x /2);
        }

    }
}