using System;

public class Program

{

    public static void Main(string[] args)

    {

        Student s1 = new Student();

        s1.Roll=1;

        s1[0]=50;

        s1[1]=50;

        s1[2]=50;

        Console.WriteLine(s1.Getpercentage());

        Student s2 = new Student();

        s2.Roll=2;

        s2[0]=50;

        s2[1]=50;

        s2[2]=50;

        Console.WriteLine(s2.Getpercentage());

    }

}

​

public class Student

{

    private int roll=10;

    public int Roll

    {

        get{return roll;}

        set{roll=value;}

    }

    private int[] marks = new int[3];

    public int this[int i]//indexer

    {

        get{return marks[i];}

        set{marks[i]=value;}

    }

    public double Getpercentage()

    {   

        double total=0.0;

        foreach(int m in marks)

        {

            total+=m;

        }

        return total/marks.Length;

    }

}