Start by naming any country that France borders. Then name any country that borders any of those countries. Then keep going until there are no more countries left to name.
Similar to my quiz: Countries with Forests http://www.jetpunk.com/user-quizzes/42254/countries-with-forests I don't have Sudan listed rather I have Mozambique and Argentina -- see http://en.wikipedia.org/wiki/List_of_countries_by_forest_area Sudan includes South Sudan so I skipped it when I made my quiz (given the land regions in the area I'm willing to guess most of the forest is in South Sudan)