public int isEqual(String num1, String num2){
		if(num1.length() < num2.length()) return -1;
		else if(num1.length() > num2.length()) return 1;
		else {
			for(int i = 0; i < num1.length(); i++){
				char ch1 = num1.charAt(i), ch2 = num2.charAt(i);
				if(ch1 < ch2) return -1;
				else if(ch1 > ch2) return 1;
			}
		}
		return 0;
	}