13. Prime Pairs

#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int firstStartNum, secondStartNum, firstEndNum, secondEndNum;
    cin >> firstStartNum >> secondStartNum >> firstEndNum >> secondEndNum;

    for (int i = firstStartNum; i <= firstStartNum + firstEndNum; i++) {
        for (int j = secondStartNum; j <= secondStartNum + secondEndNum; j++) {
            bool isFirstPrime = true;
            bool isSecondPrime = true;

            for (int k = 2; k <= sqrt(i); k++) {
                if (i % k == 0) {
                    isFirstPrime = false;
                    break;
                }
            }

            for (int k = 2; k <= sqrt(j); k++) {
                if (j % k == 0) {
                    isSecondPrime = false;
                    break;
                }
            }

            if (isFirstPrime && isSecondPrime) {
                cout << i << j << endl;
            }
        }
    }
    return 0;
}