Solution.java

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();
    }

}