remove the last "\n".your output is "sb.toString()"= "54321\n5432\n543\n54\n5\n"

I started in your same shoes, but luckily here was (and still is!) an awesome place to practice and learn :)

Thanks CM for replying ^_^

Most probably a whitespace problem. It's difficult to see them in browsers.
Make sure you are not printing any extra newline chars before or at the end of pattern.