[ BackJoon C# ]

https://www.acmicpc.net/problem/8393

8393번: 합

using System;

namespace BackJoonStudy
{
    class Program
    {
        static void Main(string[] args)
        
        {
            int N = int.Parse(Console.ReadLine());
            int j=0;
            for(int i=1; i<=N; i++)
            {
                
                j += i;
            }

            Console.WriteLine(j);
        }
    }
}