You are climbing a staircase. It takes `n` steps to reach the top.
Each time you can either climb `1` or `2` steps. In how many distinct ways can you climb to the top?
Examples
Input: n = 2
Output: 2
There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Input: n = 3
Output: 3
There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step