using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("vuvedi 3 ocenki");

        double a = double.Parse(Console.ReadLine());

        double b = double.Parse(Console.ReadLine());

        double c = double.Parse(Console.ReadLine());

        Console.WriteLine("{0}",Math.Ceiling((a+b+c)/3));

    }

}