solution(France,Switzerland,Italy,Belgium,Holland,Germany,Austria) :-
    color(France), color(Switzerland),
    \+ France=Switzerland,
    color(Italy),
    \+ France=Italy, \+ Switzerland=Italy,
    color(Belgium),
    \+ France=Belgium,
    color(Holland),
    \+ Belgium=Holland,
    color(Germany),
    \+ France=Germany, \+ Switzerland=Germany,
    \+ Belgium=Germany, \+ Holland=Germany,
    color(Austria),
    \+ Switzerland=Austria, \+ Italy=Austria,
    \+ Germany=Austria.

color(red).
color(orange).
color(yellow).