using System;

public class Program

{

    public static void Main()

    {

    Console.WriteLine("Please Enter a Positive Integer");

    string input = Console.ReadLine();

    int n = int.Parse(input);

    int sum = 0;

    for (int i = 1; i <= n; i++)

    {sum += i; }

    Console.WriteLine(sum);

    Console.ReadLine();

        }   

}