import java.util.*;

class SetTest
{
    public static void main(String [] args)
    {
      Set<Animal>s=new HashSet<Animal>();
      Animal a=new Animal(2);
      boolean b1=s.add(a);
      System.out.println("hi "+b1);

      Animal b=new Animal(2);
      boolean b2=s.add(b);
      System.out.println("hi "+b2);
    }
}


class Animal
{
    int t;
    Animal(int a)
    {
        t=a;
    }

    public boolean equals(Object O)
    {
        if(O instanceof Animal && ((Animal)O).t==t)
            return true;

        return false;
    }

    public int hashcode()
    {
        return t;
    }
}

@Override
public int hashcode()

import java.util.*;
class SetTest {
  public static void main(String [] args) {
    Set<Animal>s=new HashSet<Animal>();
   Animal a=new Animal(2);
    boolean b1=s.add(a);
    System.out.println("hi "+b1);
     Animal b=new Animal(2);
    boolean b2=s.add(b);
     System.out.println("hi "+b2);
  }
}

class Animal {
  int t;

  public Animal(int a) {
      t=a;
  }

  @Override
  public boolean equals(Object O) {
    return O instanceof Animal
            && ((Animal)O).t==t;
  }

   @Override
   public int hashCode() {
     return t;
  }
}