using System;

public class Program

{

    public static void Main()

    {

        int[] a = new int[] {1,2,3,4,5,6,7};

        int len =  0;

        len = a.Length - 1;

        int sum;

        for(sum = 0; len >= 0 ; len --)

        {

            sum = sum + a[len];

        }

        Console.WriteLine(sum);

    }

}