多层派生时的构造函数

小弟这个程序是看的书本上的,用mingw编译就是不通过.
#include<iostream>
#include<string>
using namespace std;
class Student
{
public:
Student(int n,string nam )
{
num=n;
name=nam;
}
void display()
{
cout<<"num: "<<num<<endl;
cout<<"name: "<<name<<endl;
}
protected:
int num;
string name;
};
class Student1:public Student
{
public:
Student1(int n,char nam[10],int a):Student(n,nam)
{
age=a;
}
void show()
{
display();
cout<<"age: "<<age<<endl;
}
private:
int age;
};
class Student2:public Student1
{
public:
Student2(int n,string nam,int a,int s):Student1(n,nam,a)
{
score=s;
}
void show_all()
{
show();
cout<<"score: "<<score<<endl;
}
private:
int score;
};

int main()
{
Student2 stud(10010,"li",17,89);
stud.show_all();

return 0;
}