面试题：以下程序的输出结果是

public class A {
public static void prt(){
System.out.println("1");
}
public A(){
System.out.println("A");
}

}

public class B extends A{


/**
* @param args
*/
public static void prt(){
System.out.println("2");
}
public B()
{
System.out.println("B");
}
public static void main(String[] args) {
// TODO Auto-generated method stub
A a = new B();
a = new A();
}
}

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A B  A