/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* 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 s = "(identifier1 identifier_2 23 4) ____ 33"; 
		String p = "\\b_*[a-zA-Z][_a-zA-Z0-9]*\\b";
		System.out.println(s.replaceAll(p, "$0#")); 
	}
}

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