Climbing Stairs
Given N stairs, find the number of distinct ways to reach the top, taking 1 or 2 steps at a time.
Input format
The first line contains N (1 ≤ N ≤ 60).
Output format
Print the number of ways to climb N stairs (can climb 1 or 2 stairs at a time).
Constraints
- Values fit in a 64-bit signed integer
- Trailing whitespace and a trailing newline are ignored by the judge
Read from stdin, write to stdout. Sample cases below show the exact format.
Sample cases
Example 1
Input
2Expected output
2Example 2
Input
3Expected output
3