Why monodevelop isn't being installed with Unity?

I’ve installed Unity (version 4.5.3f3) but Monodevelop ins’t being installed along with it.

Yes, I’ve tried to uninstall and reinstall it (five times).
Yes, I’ve redownloaded the install file just in case.
Yes, the option to install Mono is checked (all of them are).
Yes, I’ve tried to uncheck it and check again just in case.

The only folder inside the Unity folder is the Editor.

I’m running it with Windows 8.1. A fresh install, not upgrade. Didn’t have Unity before.

Any ideas why this is happening and how to fix it?

I don’t know why this could happen but you can download it from MonoDevelop website and configure it in Unity (Edit > Prefrences… > External Tools > External Script Editor)