写出下列程序完成的功能：
import java.io.*;
public class abc
{ public static void main(String args[])
{ SubClass sb = new SubClass( );
System.out.println(sb.max( ));
}
}
class SuperClass
{ int a = 10 , b = 20 ; }
class SubClass extends SuperClass
{ int max( ) { return ((a>b)?a:b); } }
