给出程序结果: interface Com { int add(int a, int b); } abstract class X { abstract int add(int a, int b); } class Y extends X implements Com { public int add(int a, int b) { return a + b; } } public class E { public static void main(String[] args) { Y y = new Y(); Com com = y; System.out.println(com.add(12, 6)); X x = y; System.out.println(x.add(10, 5)); } }