Set of Pairs using Java

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        TreeSet<Pair> arr = new TreeSet<>();

        arr.add(new Pair(89, 9));
        arr.add(new Pair(1, 2));
        arr.add(new Pair(1, 2));
        arr.add(new Pair(1, 2));
        arr.add(new Pair(0, 67));
        arr.add(new Pair(0, 67));
        arr.add(new Pair(0, 67));
        arr.add(new Pair(0, 67));
        arr.add(new Pair(0, 67));

        for (Pair p : arr) {
            System.out.println(p.first + " " + p.second);
        }
    }

    static class Pair implements Comparable<Pair> {
        int first;
        int second;

        Pair(int first, int second) {
            this.first = first;
            this.second = second;
        }

        @Override
        public int compareTo(Pair other) {
            if (this.first == other.first && this.second == other.second) {
                return 0;
            }
            return -1;
        }
    }
}