/* 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 = "Paper size: A4Paper size: A3Paper size: A2";
		String pattern1 = "Paper size: ([^P]*(?:P(?!aper size:)[^P]*)*)";
		Pattern ptrn = Pattern.compile(pattern1);
    	Matcher matcher = ptrn.matcher(s);
    	List<String> res = new ArrayList<>();
    	while (matcher.find())
      		res.add(matcher.group(1));
      	System.out.println(res);
	}
}

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