Arrays based program - ICSE BOARD QUESTION 2009

/*

 * The annual examination results of 50 students in a class is tabulated as follows:

 * Roll no.         Subject A            Subject B           Subject C

 * ......           .......              .......             .......

 *

 * Write a program to read the data, calculate & display the following:

 * a) Average marks obtained by each student

 * b) Print the roll no. & average marks of the students whose average mark is above 80

 * c) Print the roll no & average marks of the students whose average marks is below 40

 */

import java.io.*;
public class questionNINE2009
{
    public static void main(String args[]) throws IOException
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        int roll[]=new int[50];
        int marksA[]=new int[50];
        int marksB[]=new int[50];
        int marksC[]=new int[50];
        float avg[]=new float[50];
        int i,j;
        for(i=1; i<=50; i++)
        {
            System.out.println("Enter roll number of the student");
            roll[i]=Integer.parseInt(br.readLine());
            System.out.println("Enter marks of the student in Subject A");
            marksA[i]=Integer.parseInt(br.readLine());
            System.out.println("Enter marks of the student in Subject B");
            marksB[i]=Integer.parseInt(br.readLine());
            System.out.println("Enter marks of the student in Subject C");
            marksC[i]=Integer.parseInt(br.readLine());
           
            avg[i]=(marksA[i]+marksB[i]+marksC[i])/3;
        }
        System.out.println("----------------------------------RESULT----------------------------------------------");
        System.out.println("Roll no. \t Subject A \t Subject B \t Subject C \t Average ");
       
        for(j=1; j<=50; j++)
        {
       System.out.println(roll[j] +"\t \t" + marksA[j] +"\t \t" + marksB[j] +"\t \t" + marksC[j] +"\t \t" + avg[j] );
        }
       
        System.out.println("\n roll no. & average marks of the students whose average mark is above 80");
        System.out.println("Roll no. \t  Average ");
        for(j=1; j<=50; j++)
        {
           if(avg[j]>80)
            System.out.println(roll[j] +"\t \t" +  avg[j]);
            else
            System.out.println("N.A. \t \t   N.A.");
        }
       
        System.out.println("\n roll no. & average marks of the students whose average mark is below 40 ");
        System.out.println("Roll no. \t  Average ");
        for(j=1; j<=50; j++)
        {
           if(avg[j]<40)
            System.out.println(roll[j] +"\t \t" +  avg[j] );
            else
            System.out.println("N.A. \t \t   N.A.");
        }
           
    }
}