public static String sillyGame(int n) {

        int player = 0;
                Set<Integer> primes = new TreeSet<>();

        for (int i = 2; i <= n; i++){
            if (isPrime(i)){
                primes.add(i);
            }
        }

        if (!primes.isEmpty()){
            player = primes.size() % 2;
        }

        return player == 0 ? "Bob" : "Alice";

    }

    private static boolean isPrime(int m) {
        // Corner case
        if (m <= 1)
            return false;
        // For m=2 or m=3 it will check
        if (m == 2 || m == 3)
            return true;
        // For multiple of 2 or 3 This will check
        if (m % 2 == 0 || m % 3 == 0)
            return false;
        // It will check all the others condition
        for (int i = 5; i <= Math.sqrt(m); i = i + 6)
            if (m % i == 0 || m % (i + 2) == 0)
                return false;

        return true;
    }