protected int findOperator(String where, String op){
		int start = 0;
		int level = 0;
		for(int i=0; i<where.length(); i++){
			if(where.charAt(i) == '(')
				level++;
			else if(where.charAt(i) == ')')
				level--;
			else if(level == 0)
				if(where.charAt(i) == op.charAt(start)){
					start++;
				}else
					start = 0;
				if(start == op.length())
					return i-start+1;
		}
		return -1;
	}