水...
AC代码：
import java.util.Collections;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
/**
* @author CC11001100
*/
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
Set<String> ans = new HashSet<>();
while(sc.hasNextLine()){
Collections.addAll(ans, sc.nextLine().split("\\s+"));
}
System.out.println(ans.size());
}
}