ACMSGURU 123  The sum
The sum
Problem Description
The Fibonacci sequence of numbers is known: F1 = 1; F2 = 1; Fn+1 = Fn + Fn1, for n>1. You have to find S  the sum of the first K Fibonacci numbers.
Input
First line contains natural number K (0<K<41).
Output
First line should contain number S.
Sample Input
5
Sample Output
12
Solution
1 
