minimum([M],M).
minimum([X|T],M):-minimum(T,M),M=<X.
minimum([X|T],X):-minimum(T,M),M>X.
%--------------------get K min
getKMin(1,L,M):-minimum(L,M),!.
getKMin(K,L,M):-minimum(L,Q),delFirst(L,Q,Lnew),Knew is K-1,getKMin(Knew,Lnew,M).

%---------------------delete first element list
delFirst([X|T],X,T):-!.
delFirst([N|T],X,[N|L]):-delFirst(T,X,L).

%---------------------get SecondMin
secondMin(L,M):-getKMin(2,L,M).