Problems
Fibonacci Sequence
Fibonacci Sequence
The Fibonacci sequence is defined as follows:
a0= 0a1= 1ak=ak-1+ak-2
For a given value of n find the n-th element of an Fibonacci sequence.
Input
One positive integer n (1 ≤ n ≤ 40).
Output
Print the n-th element of the Fibonacci sequence.
Input example #1
2
Output example #1
1
Input example #2
5
Output example #2
5
Input example #3
8
Output example #3
21