Fibonacci in C++

#include <iostream>

using namespace std;
int fib(int n) // Take an n value
{
if (n == 0 || n == 1) return 1;
// Fib(0) and Fib(1) are equal to 1
return fib(n-1) + fib(n-2);
}
main()
{
int n;
cout << "Non-Negative Integer Please : ";
cin >> n;
cout << "Fibonacci(" << n << ") = " << fib(n) << "." << endl;
return 0;
}