import java.util.Comparator;
import java.util.TreeSet;

class Student implements Comparable {
	String nume;
	double media;
	int clazz;

	public Student (String n, double m, int c) {
		nume = n;
		media = m;
		clazz = c;
	}

	@Override
	public int compareTo(Object a) {
//          Student st = (Student)arg0;
//          if(media < st.media)
//              return 1;
//          if(media > st.media)
//              return -1;
//          return (nume.compareTo(st.nume));
//		return 1;
		return this.nume.compareTo(((Student)a).nume);
	}

	public boolean equals(Object other) {
		return this.nume.equals(((Student)other).nume);
	}

	public String toString() {
		String s = "";
		s = s + "{Nume: " + nume + ", media: " + media + ", grupa: " + clazz +"}";
		return s;
	}

}

public class Catalog extends TreeSet<Student> {


    public Catalog (Comparator comparator) {
       TreeSet<Student> t = new TreeSet<>(comparator);
    }

    public Catalog () {
    	TreeSet<Student> t = new TreeSet<>();
    }

    public void addStudent(String name, double media, int clazz) {
        add(new Student(name, media, clazz));
    }

    public Student getStudent(String name) {
        for(Student i : this)
            if(i.nume.equals(name) )
                return i;
        return null;
    }

    public void removeStudent (String name) {
    	remove(getStudent(name));
    }

    public Catalog byClass (int clazz ) {
        Catalog c = new Catalog();

        for(Student i : this)
            if(i.clazz == clazz)
                c.add(i);
        return c;
    }

    public String toString() {
        String s = "";
        for(Student i : this)
            s = s + i + "\t";
        return s;
    }
}