Substitute

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = Integer.parseInt(scanner.nextLine()),
                b = Integer.parseInt(scanner.nextLine()),
                c = Integer.parseInt(scanner.nextLine()),
                d = Integer.parseInt(scanner.nextLine()),
                counter = 0;

        for (int k = a; k < 9; k++) {
            for (int l = 9; l >= b; l--) {
                for (int m = c; m < 9; m++) {
                    for (int n = 9; n >= d; n--) {
                        if (k % 2 == 0 && m % 2 == 0 && l % 2 == 1 && n % 2 == 1) {
                            if (k == m && l == n) {
                                System.out.println("Cannot change the same player.");
                            } else {
                                System.out.printf("%d%d - %d%d\n", k, l, m, n);
                                if (++counter == 6) {
                                    System.exit(0);
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}