Java Inheritance I

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();
   }

}