private int getCompositeNum() {
		int n = 1;
		List<Integer> primes = new ArrayList<>();
		while ((n += 2) > 0) {
			boolean isPrime = Problem3.isPrime(n);
			if (isPrime) {
				primes.add(n);
				continue;
			}
			boolean hit = false;
			for (int i = primes.size() - 1; i >= 0; i--) {
				int p = primes.get(i);
				int sub = (n - p) / 2;
				int j = 0;
				while (++j > 0) {
					int square = (int) Math.pow(j, 2);
					if (square < sub) {
						continue;
					} else {
						if (square == sub) {
							hit = true;
						}
						break;
					}
				}
				if (hit) {
					break;
				}
			}
			if (!hit) {
				return n;
			}
		}
		return -1;
	}