import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class DuplicateString {

    public static boolean hasDuplicateWords(String sentence) {

        String[] words = sentence.split(" ");


        Set<String> seenWords = new HashSet<>();


        for (String word : words) {

            if (!seenWords.add(word)) {
                return true;
            }
        }


        return false;
    }

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);


        System.out.println("Enter a sentence:");
        String sentence = scanner.nextLine();


        if (hasDuplicateWords(sentence)) {
            System.out.println("The sentence contains duplicate words.");
        } else {
            System.out.println("The sentence does not contain duplicate words.");
        }


    }
}