magic number game solution

import java.io.*;

public class magicnumber {

    public static void main(String[] args) throws IOException{

        //gets input as a string
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("input an integer to play, input 'q' to quit");
        String in = null;
        try{
            do{
                in = br.readLine();
                //checks for exit case or empty line to avoid errors
                if(!(in.equals("q")||in.equals("")))
                    //starts the game and outputs the magic number phrase when it's done
                    System.out.println(playMagicNum(in));
            }while(!(in.equals("q")||in.equals("")));
            //loop ends here
        } catch(IOException ioe){
            System.out.println("IO error");
             System.exit(1);
        }

        System.out.println("thanks for playing!");


    }

    public static String playMagicNum(String input){
        String out = ""; //second number in strings
        String in = ""; //first number in strings
        int count = 0; //integer outputs of string lengths. or how many characters in each number
        String sTemp = ""; //stores each number converted to string
        in = input;
        //seed the loop with the first number
        sTemp = convert(Integer.parseInt(in));
        //will loop until the sTemp value starts with 'four' meaning the last word used was 'four'
        while(!(sTemp.equals("four"))){
            //counts the length of the first number, and passes the word to the output
            count = sTemp.length();
            in = sTemp;
            //converts the length of the first number into a word, then passes it to the output
            sTemp = convert(count);
            out = sTemp;
            //output the word-pairs
            System.out.println(in+" is "+out);
        }
        return "4 is the magic number";
    }

    /*
     * int-to-word conversion methods were found at http://stackoverflow.com/questions/3911966/how-to-convert-number-to-words-in-java
     */

     public static final String[] units = {
         "", "one", "two", "three", "four", "five", "six", "seven",
         "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen",
         "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
      };

     public static final String[] tens = {
             "",        // 0
             "",        // 1
             "twenty",  // 2
             "thirty",  // 3
             "forty",   // 4
             "fifty",   // 5
             "sixty",   // 6
             "seventy", // 7
             "eighty",  // 8
             "ninety"   // 9
     };

     public static String convert(final int n) {
         if (n < 0) {
             return "minus " + convert(-n);
         }

         if (n < 20) {
             return units[n];
         }

         if (n < 100) {
             return tens[n / 10] + ((n % 10 != 0) ? " " : "") + units[n % 10];
         }

         if (n < 1000) {
             return units[n / 100] + " hundred" + ((n % 100 != 0) ? " " : "") + convert(n % 100);
         }

         if (n < 1000000) {
             return convert(n / 1000) + " thousand" + ((n % 1000 != 0) ? " " : "") + convert(n % 1000);
         }

         if (n < 1000000000) {
             return convert(n / 1000000) + " million" + ((n % 1000000 != 0) ? " " : "") + convert(n % 1000000);
         }

         return convert(n / 1000000000) + " billion"  + ((n % 1000000000 != 0) ? " " : "") + convert(n % 1000000000);
     }



}