import java.util.regex.*;
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String regex = "[\\w&&[\\D]][\\w-]*";
		Pattern pattern = Pattern.compile(regex);
 
		String s1 = "hello world";
		String s2 = "_Sau90-jds";
		String s3 = "5_idsjd";
		String s4 = "A-next";
 
		ArrayList<String> list = new ArrayList<>();
		list.add(s1);
		list.add(s2);
		list.add(s3);
		list.add(s4);
 
		for (String string : list) {
		    Matcher matcher = pattern.matcher(string);
		    if (matcher.matches()) {
		        System.out.println(matcher.group(0));
		    }
		}
	}
}

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