Virtual base class C++ program to display the pattern like a diamond

Write a program in C++ to display the pattern like a diamond by using the virtual base class in object oriented programming.

# include<iostream>
using namespace std;
class a
{
	public:
		int n;
		public:
			a()
			{
				n=4;
			}
};
class b:public virtual a
{
	public:
		int i;
};
class c:virtual public a
{
	public:
		int s;
};
class d: public b,c
{
	int j;
public:
	int show()
	{
		for(i=1;i<=n;i++)
		{
			for(s=i;s<n; s++)
			{
				cout<<" ";
			}
			for(j=1;j<=2*i-1;j++)
			{
				cout<<"*";
			}
			cout<<endl;
		}
	}
	};
	int main()
	{
		d obj;
		obj. show();
	}