10. Extract All Unique Words

import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;


public class _10_ExtractAllUniqueWords {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] words = sc.nextLine().toLowerCase().split("\\W+");
        Set<String> uniqueWords = new TreeSet<>();
        for (String word : words) {
            if (!uniqueWords.contains(word)) {
                uniqueWords.add(word);
            }
        }
        for (String word : uniqueWords) {
            System.out.print(word + " ");
        }
    }
}