insert_sort(List,Sorted):-i_sort(List,[],Sorted).
i_sort([],Acc,Acc).
i_sort([H|T],Acc,Sorted):-insert(H,Acc,NAcc),i_sort(T,NAcc,Sorted).
   
insert(X,[Y|T],[Y|NT]):-X>Y,insert(X,T,NT).
insert(X,[Y|T],[X,Y|T]):-X=<Y.
insert(X,[],[X]).