ON JAVA 7;

import java.io.; import java.util.; import java.text.; import java.math.; import java.util.regex.*;

class Animal{ void walk(){ System.out.println("I am walking"); } }

class Bird extends Animal{ void fly(){ System.out.println("I am flying"); } void sing(){ System.out.println("I am singing"); } }

public class Solution{

public static void main(String args[]){

  Bird bird = new Bird();
  bird.walk();
  bird.fly();
  bird.sing();

} }