SP10676 IWGBS - 0110SS

Description

Dor is IWGolymp student so he has to count in how many ways he can make **N** digit numbers that is formed by ones and zeroes. But zeroes can not be next to each other. Help to him in how many different numbers can he make. For example, **N** = 3: 101, 010, 111, 110, 011 **Note:** A leading zero is allowed.

Input Format

A positive integer **N** (1

Output Format

Answer for the problem.