Hi, this is my solution but always marks error, any advice?

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

class Main{

public static void main(String[] args) {

    // Regular expression to match repeated words
    String regex = "\\b(\\w+)(\\s+\\1\\b)+";

    Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
    Scanner in = new Scanner(System.in);
    int numSentences = Integer.parseInt(in.nextLine());

    while (numSentences-- > 0) {
        String input = in.nextLine();

        Matcher m = p.matcher(input);

        // Check for subsequences of input that match the compiled pattern
        while (m.find()) {
            input = input.replaceAll(m.group(), m.group(1));
        }

        // Prints the modified sentence.
        System.out.println(input);
    }

    in.close();
}

}