Belah Ketupat Kosong C++

#include <iostream.h>

main()
{
int a, b, c, d;
cout<<"input = ";
cin>>a;
for (b=a;b>=1;b--)
{
for (c=1;c<b;c++)
{cout<<" ";}
cout<<"*";
for (c=b;c<a-1;c++)
{cout<<" ";}
for (c=b;c<a;c++)
{cout<<" ";}
if (b<a)
cout<<"*";
cout<<endl;
}

for (b=a;b>=1;b--)
{
if (b<a)
{ for (c=a;c>b;c--)
{cout<<" ";}
cout<<"*";
for (c=b-1;c>1;c--)
{cout<<" ";}
for (c=b;c>1;c--)
{cout<<" ";}
if (b>1)
cout<<"*";
cout<<endl;}
}}