静态成员变量和类型转换构造函数的题，求帮助

代码填空，使得程序能够自动统计当前各种动物的数量，只能在橙色的两句话中间填写代码，红色那一句不知道怎么处理，求大佬看一下。
#include <iostream>
using namespace std;
class Animal{
    public:
        static int number;
};

class Cat{
    public:
        static int number;
        Cat(){
            number++;
            Animal::number++;
        }
        ~Cat(){
            number--;
            Animal::number--;
        }
};

class Dog{
    public:
        static int number;
        Dog(){
            number++;
            Animal::number++;
        }
        ~Dog(){
            number--;
            Animal::number--;
        }
};
            
int Animal::number=0;
int Cat::number=0;
int Dog::number=0;

void print() {
    cout << Animal::number << " animals in the zoo, " << Dog::number << " of them are dogs, " << Cat::number << " of them are cats" << endl;
}

int main() {
    print();
    Dog d1, d2;
    Cat c1;
    print();
    Dog* d3 = new Dog();
    Animal* c2 = new Cat;//这里不知道怎么处理实现
    Cat* c3 = new Cat;
    print();
    delete c3;
    delete c2;
    delete d3;
    print();
}
输入
无
输出
0 animals in the zoo, 0 of them are dogs, 0 of them are cats
3 animals in the zoo, 2 of them are dogs, 1 of them are cats
6 animals in the zoo, 3 of them are dogs, 3 of them are cats
3 animals in the zoo, 2 of them are dogs, 1 of them are cats