Climbing Stairs

You are climbing a staircase. It takes n steps to reach the top. Each time you can climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Example 1:

Input:  n = 2
Output: 2
Explanation: 1+1 or 2

Example 2:

Input:  n = 3
Output: 3
Explanation: 1+1+1, 1+2, or 2+1

Constraints:

• 1 <= n <= 45