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// Created by Julio Tentor <[email protected]>
//
import java.lang.Comparable;
 
public class Person implements Comparable<Person> {
    private String lastname;
    private String firstname;
 
    public Person() {
        this("", "");
    }
    public Person(String lastname, String firstname) {
        this.lastname = lastname;
        this.firstname = firstname;
    }
 
    @Override
    public String toString() {
        return this.lastname +  ", " + this.firstname;
    }
 
    @Override
    public int compareTo(Person o) {
        return this.toString().compareTo(o.toString());
    }
}