Ackermann's Function (Super slow with std::cout, Instant with out std::cout, why? )

[WetCode]

Ok so today I got a weird one.
How come if I cout the values this can take forever to finish.
But when removing std::cout and only doing the math its done in a instant.?
Is STL really "this slow" or did I do something wrong.

BTW this is Ackermann's Function
Wiki: http://en.wikipedia.org/wiki/Ackermann_function

Here is the code:
(Refrence / Credits:
http://www.daniweb.com/software-development/cpp/threads/327087/ackermanns-function-in-c )

#include <iostream>
#include <Windows.h>

using namespace std;
int A(int, int);
int main()
{
	int m, n;
	cout<<"Enter a value for m: ";
	cin>>m;
	cout<<"Enter a value for n: ";
	cin>>n;

	A(m,n);

	system("PAUSE");

	return 0;
}
int A(int m,int n)
{
	if (m==0)
	{
		cout<<"A("<<m<<","<<n<<") ";
		return n+1;
	}
	else if (n==0)
	{
		cout<<"A("<<m<<","<<n<<") ";
		return A(m-1,1);
	}
	else
	{
		cout<<"A("<<m<<","<<n<<") ";
		return A(m-1, A(m,n-1));	
	}
}

If anyone can explain this to me it would be great.

Cheers
WetCode

[Disch]

Is STL really "this slow" or did I do something wrong.

It's not STL... it's just console output in general. And yes, it can be that slow.

Printing (and flushing) is slow.

[WetCode]

Ok thanks for your reply.
Cheers