Substitute Java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Substitute {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int k = Integer.parseInt(reader.readLine());
        int l = Integer.parseInt(reader.readLine());
        int m = Integer.parseInt(reader.readLine());
        int n = Integer.parseInt(reader.readLine());

        int substitute = 0;

        for (int i = k; i <= 8; i++) {
            for (int j = 9; j >= l; j--) {
                for (int o = m; o <= 8; o++) {
                    for (int p = 9; p >= n; p--) {
                        if (i % 2 != 0 || o % 2 != 0 || j % 2 == 0 || p % 2 == 0) {
                            continue;
                        } else if (i == o && j == p){
                            System.out.println("Cannot change the same player.");
                        } else {
                            substitute++;
                            System.out.println("" + i + j + " - " + o + p);
                        }

                        if (substitute >= 6){
                            return;
                        }
                    }
                }
            }
        }
    }
}