public static boolean stringIntersect(String a, String b, int len) {
		
		if (len <= 0)
			return false;
		if (a.length() < len || b.length() < len)
			return false;
		
		Set<String> subSetA = new HashSet<String>();
		int posA = 0;
		int posB = 0;
		for (; posA + len < a.length(); posA += 1) {
			subSetA.add(a.substring(posA, posA+len));
		}
		
		for (; posB + len < b.length(); posB += 1)
			if (subSetA.contains(b.substring(posB, posB+len)))
				return true;		
		return false; // YOUR CODE HERE
	}