13. Prime Pairs

import java.util.Scanner;

public class PrimePairs {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int firstStart = Integer.parseInt(scanner.nextLine()),
                secondStart = Integer.parseInt(scanner.nextLine()),
                firstDiff = Integer.parseInt(scanner.nextLine()),
                secondDiff = Integer.parseInt(scanner.nextLine());

        for (int i = firstStart; i <= firstStart + firstDiff; i++) {
            for (int j = secondStart; j <= secondStart + secondDiff; j++) {
                boolean isFirstPrime = true, isSecondPrime = true;
                for (int k = 2; k <= Math.sqrt(i); k++) {
                    if (i % k == 0) {
                        isFirstPrime = false;
                        break;
                    }
                }
                for (int k = 2; k <= Math.sqrt(j); k++) {
                    if (j % k == 0) {
                        isSecondPrime = false;
                        break;
                    }
                }
                if (isFirstPrime && isSecondPrime) {
                    System.out.printf("%d%d\n", i, j);
                }
            }
        }
    }
}