UVA - 389 - Basically Speaking

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        StringBuffer sb = new StringBuffer("");
        String m = "";
        while ((m = br.readLine()) != null) {
            StringTokenizer st=new StringTokenizer(m);
            String[] str = new  String[st.countTokens()];
            for(int i=0;i<str.length;i++){
                str[i]=st.nextToken();
            }
            int baseFrom=Integer.parseInt(str[1]);
            int baseTo=Integer.parseInt(str[2]);
            int temp=Integer.parseInt(str[0],baseFrom);
            StringBuilder result=new StringBuilder(Integer.toString(temp, baseTo));
            for(int i=result.length();i<7;i++){
                result.insert(0, ' ');
            }
            if(result.length()==7)
                sb.append(result.toString().toUpperCase()).append("\n");
            else
                sb.append("  ERROR\n");
        }
        System.out.print(sb);
    }
}