Please advise on why test case fails even though output matches. I believe its an minor mistake.

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();
        List<String> list = Arrays.asList(input.split(" "));
        Set<String> ans = new HashSet<>();  
        String answer = list.stream()
        .filter(str -> ans.add(str.toLowerCase()))
        .collect(Collectors.joining(" ")).trim();        
        System.out.println(answer);
        numSentences--;
    }

    in.close();
}

}