using System;

public class Program

{

    public static void Main()

    {

        int[] a = new[]{2,8,5};

        int n = a.Length;

        int sum = 0;

        int count = 0;

        while(count < n)

        {

            sum = sum + a[count];

            count = count + 1;

        }

        int result = 0;

        while(sum >= count)

        {

            sum -= count;

            result += 1;

        }

        Console.WriteLine(result.ToString());

    }

}