What will be printed out as a result of the following code execution?

#include <iostream>
using namespace std;

class B {
    public: virtual void msg () { cout << "classB"; }
};

class D : public B {
    public: virtual void msg() { cout << "classD"; }
};

int main() {
    B * var = new D;
    var->msg();
    // ....
    return 0;
}