read_data(X):-
see('pe67.txt'),
read(X),
seen.
max(A,B,A):-A>B,!.
max(_,B,B):-!.
calc_row([X],[Y],[Z]):-
!,
Z is X+Y.
calc_row([X,Y|Rest],[Z|Rest1],[Z1|Result]):-
max(X,Y,Add),
Z1 is Z+Add,
calc_row([Y|Rest],Rest1,Result).
calc(DP,[]):-
!,
sort(DP,DP1),
reverse(DP1,[Ans|_]),
write(Ans).
calc(DP,[RowA|Rest]):-
[L|RowB]=RowA,
calc_row(DP,RowB,DP1),
[L2|_]=DP,
L3 is L2+L,
calc([L3|DP1],Rest).
main:-
read_data([Top|Rest]),
calc(Top,Rest).
