Caring owners of the apartment take care of the cockroach Vasily. In the evening they lay out a row of
N breadcrumbs for him, which he loves very much. Passing from one bread crumb to another, the cockroach Vasily may or may not eat it. But he never eats two breadcrumbs in a row.
Count how many different options for eating bread crumbs the cockroach Vasily has.
Input
The program input an integer N (\(1<=N<=100\) ).
Output
Print the answer to the problem.
Examples