Perulangan While Pada C++ 8

#include <iostream.h>
#include <conio.h>
main()
{
clrscr;
int n,p,o;
o=1;
p=1;
cout<< "input n: ";
cin>> n;
while (o<=n)
{
p=1;
while (p<=o)
{
cout<<"*";
p++;
}
cout<<endl;
o++;
}
n--;
while (n>=1)
{
p=n;
while (p>=1)
{
cout<<"*";
p--;
}
cout<<endl;
n--;
}
getch();
return 0;
}