class A {
 
public void m1(){
    mx();
}
 
public static void main(String[] args){
 
    try {
        A a = ( B) new C(); 
        a.m1();
        B b = (B) new A(); 
        b.m1();
    } catch (Exception e) {
        e.printStackTrace(System.out);
    }
}
 
public void mx(){ 
     System.out.print(10);
}
}
 
 
class B extends A{
public void mx(){
    System.out.print(30);
}
}
 
class C extends B {
public void mx(){
    System.out.print(40);
}
}

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