/* 
Laura Toma
csci107

Write a recursive method fib that computes the nth Fibonacci numbers
(fib(n)). The Fibonacci numbers are defined as follows:

fib(0) = 0
fib(1) = 1
fib(n) = fib(n-1) + fib(n-2) if n>1

Suggested test inputs (correct answer after arrow): 

fib(0) => 0
fib(1) => 1
fib(2) => 1
fib(3) => 2
fib(4) => 3
fib(10) => 55
fib(20) => 6765

*/

#include <iostream.h>


/* compute and return the n-th fibonacci number */
int fibonacci(int n) {
  if (n < 0) {
    cout << "oops. must be positive.." << endl; 
    exit(1); 
  }
  if (n == 0) return 0; 
  if (n == 1) return 1; 

  //note that it can ONLY get here if n != 0 AND n != 1, so we dont
  //need an 'else'..
  return fibonacci(n-1) + fibonacci(n-2); 
}


int main() {

  int n;
  cout << "n="; 
  cin >> n; 
  cout << "fib(" << n << ")=" << fibonacci(n) << endl;
  
  return 0; 
}