import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
 
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String regex = "\\b[a-z]\\d*\\b";
		String s = "((x0+(2.0^x))/(21.1-x0))";
		List<String> matches = new ArrayList<String>();
		Matcher m = Pattern.compile(regex, Pattern.CASE_INSENSITIVE).matcher(s);
 
		while (m.find()) {
			matches.add(m.group());
		}
 
		for (String match : matches) {
    		System.out.println(match);
		}
	}
}

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