using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("number of students:");

        int s = int.Parse(Console.ReadLine());

        int[] g = new int[s];

        for (int i = 0; i < 3; i++)

        {

            for (int j = 0; j < s; j++)

            {

                Console.WriteLine("student {0}, grade {1} is:", j + 1, i + 1);

                int gr = int.Parse(Console.ReadLine());

                g[j] += gr;

            }

        }

​

        for (int j = 0; j < s; j++)

        {

            Console.WriteLine("student {0} average: {1}", j + 1, (g[j] / 3));

        }

    }

}