13.6. Количество слов в тексте.

package untitled;

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

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int counter = 0;
        HashSet<String> set = new HashSet<>();
        String string = sc.nextLine();

        for (String s : string.split(" "))
            if (!s.trim().equals(""))
                set.add(s);
        System.out.println(set.size());
    }
}