code give right output but still wrong why???

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern;

public class DuplicateWords {

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int numSentences = Integer.parseInt(in.nextLine());

while (numSentences-- > 0) {
    String input = in.nextLine();
    String regex = "\\b(\\w+)(\\s+\\1\\b)+";

    Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);

    Matcher m = p.matcher(input);
    String output = m.replaceAll("$1");

    System.out.println(output);
}

in.close();

} }