package javaapplication1;
import java.util.HashSet;
public class JavaApplication1 {
public static void main(String[] args) {
try {
HashSet<String> hash = new HashSet<>();
hash.add("java");
hash.add("c");
hash.add("c++");
hash.add("c++");
hash.add("php");
System.out.println("size: " + hash.size());
if (hash.isEmpty())
System.out.println("yes");
else
System.out.println("no");
} catch (Exception e) {
System.out.print(e.toString());
}
}
}
/*
run:
size: 4
no
*/