请看下列代码，程序的输出结果是：(     )

class One {
    public One() { System.out.print(1); }
}
class Two extends One {
    public Two() {System.out.print(2); }
}
class Three extends Two {
    public Three() { 
        System.out.print(3); 
    }
}
public class Numbers {
    public static void main(String[] argv) { 
        new Three(); 
    }
}