Fibonacci Sequence

Given a positive integer n, compute the nth term in the Fibonacci sequence. For those of you that have been living under a rock in the mathematical world, here's the definition:

• The first and second terms are 1.
• nth term is the (n-1)th term + the (n-2)th term. So the 3rd term is the 1st term + the 2nd term, the 4th term is the 3rd term + the 2nd term, etc.

Thus the sequence looks like this: 1, 1, 2, 3, 5, 8, 13, 21, ...

Examples

fibo(1) ➞ 1

fibo(2) ➞ 1

fibo(3) ➞ 2

fibo(6) ➞ 8

fibo(30) ➞ 832040

Notes

N/A