import java.util.HashSet; import java.util.Set;
public class Program {
public static void main(String[] args) {
Set<String> alunos = new HashSet<>();
alunos.add("Rogerio");
alunos.add("Stefanny");
System.out.println(alunos.size());
alunos.add("Rogerio");
System.out.println(alunos.size());
}
}