## Hints
For this exercise the following F# feature comes in handy:
- [Tail recursion](https://blogs.msdn.microsoft.com/fsharpteam/2011/07/08/tail-calls-in-f/) Prevent stack overflows with large input by using tail recursion. While there are no test cases checking explicitly for this, using tail recursion leads to a more performant solution.
## Hints
For this exercise the following F# feature comes in handy:
- [Tail recursion](https://blogs.msdn.microsoft.com/fsharpteam/2011/07/08/tail-calls-in-f/) Prevent stack overflows with large input by using tail recursion. While there are no test cases checking explicitly for this, using tail recursion leads to a more performant solution. Another good resource on tail recursion is [this blog post](http://blog.ploeh.dk/2015/12/22/tail-recurse/).

Add another good tail recursion reference
Add another good tail recursion reference