codeforces 614A LinkOrCutTree program in java

LinkOrCutTree.java

import java.math.BigInteger;
import java.util.Scanner;

public class LinkOrCutTree
{
    public static void main(String[] args)
    {
        Scanner z=new Scanner(System.in);
        BigInteger bl=new BigInteger(z.next());
        BigInteger br=new BigInteger(z.next());
        BigInteger bk=new BigInteger(z.next());
        int i=0;
        BigInteger ba;
        String x="";
        while(true)
        {
            ba=bk.pow(i);
            if(ba.compareTo(br)==1)
                break;
            if((ba.compareTo(bl)==0 || ba.compareTo(bl)==1) && (ba.compareTo(br)==0 || ba.compareTo(br)==-1))
                x+=ba+" ";
            i++;
        }
        if(x.length()/2==0)
            System.out.println("-1");
        else
            System.out.println(x.trim());
        z.close();
    }
}