Solve the programming task below in a Python markdown code block.
Given a side length `n`, traveling only right and down how many ways are there to get from the top left corner to the bottom right corner of an `n by n` grid?

Your mission is to write a program to do just that!

Add code to `route(n)` that returns the number of routes for a grid `n by n` (if n is less than 1 return 0).

Examples:
    
    -100 -> 0
    
    1 -> 2
     
    2 -> 6
     
    20 -> 137846528820
    
Note: 
you're traveling on the edges of the squares in the grid not the squares themselves.

PS.If anyone has any suggestions of how to improve this kata please let me know.
Also feel free to reuse/extend the following starter code:
```python
def routes(n):
```