// Author:  Keith Shomper
// Date:    11/4/03
// Purpose: To demonstrate a recursive program with the Fibonacci sequence

#include <iostream>

using namespace std;

int main() {
	int    fibonacci(int n);
	string suffix(int n);

	int   n, f;

	// prompt the user for the value of N 
	cout << "Which Fibonacci number would you like to compute ?  ";
	cin  >> n;

	f = fibonacci(n);

	// Display the result
	if (f > 0) {
		cout << "The " << n << suffix(n) << " Fibonacci number is " << f << endl;
	}

	return 0;
}

int fibonacci(int n) {
	if (n <= 0) {
		cerr << "Error:  Fibonacci number not defined for non-positive number " << n << endl;
		return 0;
	} else if (n==1 || n==2) {
		return 1;
	} else {
		return fibonacci(n-1) + fibonacci(n-2);
	}
}

string suffix(int n) {
	string s;

	switch (n%10) {
		case 1:  if (n%100 == 11) {
				s= "th";
			 } else {
				s= "st";
			 }
			 break;
		case 2:  if (n%100 == 12) {
				s= "th";
			 } else {
				s= "nd";
			 }
			 break;
		case 3:  if (n%100 == 13) {
				s= "th";
			 } else {
				s= "rd";
			 }
			 break;
		default: s = "th";
			 break;
	}

	return s;
}