public int readValue(int base, String s){
        boolean negative;
        char ch;
        int number = 0;
        int index = 0;
        do{
            //read (ch) 
            ch = s.charAt(index++);
        }while (ch <= ' ');
            if (ch == '-'){
                negative = true; 
                //read (ch) 
                ch = s.charAt(index++);
            }else{
                negative = false;
            if (ch == '+') { 
                //read (ch) 
                ch = s.charAt(index++);
            }
        }
        //while (value(ch),base){
        while (index < s.length()){
            //number = number * base + value(ch);
            number = number * base + (int)ch;
            //read (ch) 
            ch = s.charAt(index++);
        }
        if (negative) {
            number = -number;
        }
        return number;
    }