public class BaseNumber {
    int base;
    Digit list;
    public BaseNumber(int value) {
        base = 10;
        list = listInBase(10, value);
    }
    BaseNumber(int base, Digit list) {
        this.base = base;
        this.list = list;
    }
    Digit listInBase(int base, int n) {
        if (n == 0)
            return new Digit(0,null);
        else {
            Digit ls = null;
            while (n != 0) {
                ls = new Digit(n % base, ls);
                n /= base;
            }
            return ls;
        }
    }
    public int toInt() {  // uses Horner's method
        Digit ls = list;
        int result = 0;
        while (ls != null) {
            result = (result * base) + ls.number;
            ls = ls.next;
        }
        return result;
    }

    public BaseNumber toBase(int b) { // 2 <= b <= 10 
        return new BaseNumber(b, listInBase(b, toInt()));
    }
    public BaseNumber plus(BaseNumber x) {
        return new BaseNumber(toInt() + x.toInt());
    }
    public BaseNumber times(BaseNumber x) {
        return new BaseNumber(toInt() * x.toInt());
    }
    public String toString() {
        return ("" + list + " base " + base);
    }
}

class Digit {
    int number;
    Digit next;
    Digit(int n, Digit next) {
        number = n;
        this.next = next;
    }
    public String toString() {
        if (next == null)
            return "" + number;
        else
            return "" + number + next;
    }
}