OOP2 Abstract Class (C++)

#include <cstdlib>
#include <iostream>

using namespace std;

class A
{
public :
    virtual void Nama(string nm) = 0;
    virtual void NIM(int nim) = 0;

};

class B : public A
{
public :
    void Nama(string nm)
    {
        cout << "Nama Mahasiswa = "<<nm << endl;
    }
    void NIM(int nim)
    {
        cout << "NIM = "<<nim << endl;
    }
};

int main(int argc, char *argv[])
{
B b;
b.Nama("Joko Prasetyo");
b.NIM(1113101102);
system("PAUSE");
return EXIT_SUCCESS;
}