下列程序的输出结果是非曲直 【15】 。#include＜iostream, h＞class base{ int x, y;public: base(int i, int j){x=i; y=j;} virtual int add(){return x+ y;}};class three: public base{ int z;public: three(int i, int j, int k) :base(i, j){z=k; } int add() { return (base:: add()+z); }};void main(){ three * q=new three(lO,20,30); cout＜＜q-＞add()＜＜end1;}