public class numerePrime {
    public static void main(String[] args) {
        PrimeChecker check = new PrimeChecker();

        for (int i = 0; i < 20; ++i) {
            if (check.isPrime(i) == true) {
                System.out.println(i + " este prim");
            }
            else {
                System.out.println(i + " nu este prim");
            }
        }
    }
}

class PrimeChecker {
    public boolean isPrime(int number) {
        if (number == 0 || number == 1) return false;
        if (number % 2 == 0 || number % 3 == 0) return false;

        for (int i = 5; i <= Math.sqrt(number); i += 6) {
            if (number % i == 0 || number % (i + 2) == 0) return false;
        }
        return true;
    }
}