Map Colouring

In this puzzle you asked to colour countries on the map in such a way that no two countries with a shared border are the same colour. Superficially, it looks like a simple colouring exercise, but by applying constraints the problem becomes much more challenging. There are a lot of conditions that could be imposed; the one chosen here is that you should use as little as possible of the fourth colour (as measured by accumulated area). Try to find this minimal solution. Your attempt is automatically checked once the map is fully shaded and without colour clashes.

Map #1