using System;

public class Program

{

    public static void Main()

    {

        int m1,m2,m3,m4, avg;

        Console.WriteLine("Input 4 numbers");

        m1=Convert.ToInt32(Console.ReadLine());

        m2=Convert.ToInt32(Console.ReadLine());

        m3=Convert.ToInt32(Console.ReadLine());

        m4=Convert.ToInt32(Console.ReadLine());

        avg=(m1+m2+m3+m4)/4;

        Console.WriteLine(avg);

    }

}