单选题 有如下程序：
#include＜iostream＞
using namespace std;
class Base {
int x;
public:
Base(int n=0): x(n) {cout＜＜n;}
int getX()const {return x;}
};
class Derived: public Base {
int y;
public:
Derived(int m, int n): y(m), Base(n) {cout＜＜m;}
Derived(int m): y(m) {cout＜＜m;}
};
int main()
{
Derived d1(3), d2(5, 7);
return 0;
}
执行这个程序的输出结果是______。