Solution of Challenge - 1

import java.io.*;
import java.util.*;
public class Main 
{
 public static void main(String[] args) {
  String Data[] = new String[10];
  int splitData[][] = new int[10][2];

  Scanner sc = new Scanner(System.in);
  System.out.println("Enter 10 records...");
  for (int i = 0; i < 10; i++) {
   Data[i] = sc.next();
   String str[] = Data[i].split("-");

   //Copy given data into two-D array

   splitData[i][0] = Integer.parseInt(str[1]);
   splitData[i][1] = Integer.parseInt(str[0]);
  }

  Arrays.sort(splitData, new Comparator < int[] > () {
   public int compare(int[] o1, int[] o2) // Sorting of array
    {
     return o2[0] - o1[0];
    }
  });

  Byte flag = 0;
  System.out.println("Output Result");
  for (int i = 0; i < 10; i++) {
   flag = 0;
   for (int j = i - 1; j >= 0; j--) //Logic to check duplicate roll no
   {
    if (splitData[i][1] == splitData[j][1]) {
     flag = 1;
     break;
    }
   }
   if (flag == 0) {
    System.out.println(splitData[i][1] + "-" + splitData[i][0]);
   }
  }
 }
}