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 = "(?<!^\\d{2})\\d(?=[\\d-]*\\d-?\\d-?\\d$)";
		Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
		String strings[] = { "7108898787654351", "7108-8987-8765-4351"};
 
		for (String s : strings) {
			Matcher matcher = pattern.matcher(s);
    		System.out.println(matcher.replaceAll("*"));
		}
	}
}

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