private static boolean hasCommon(int i, int j){
		Set<Character> seen = new HashSet<Character>();
		for(char c : Integer.toString(i).toCharArray()){
			seen.add(c);
		}
		for(char c : Integer.toString(j).toCharArray()){
			if(c!='0' && seen.contains(c)) return true;
		}
		return false;
	}