input([8, 9, 2, 1, 9, 5, 9, 6, 9, 9, 9, 1, 7, 3, 5, 8, 3, 7, 9, 1, 5, 2, 7, 3, 8, 6, 8, 7, 2, 9, 5, 4, 8, 6, 9, 4, 2, 3, 7, 9, 6, 7, 4, 9, 5, 1, 1, 5, 4, 1, 2, 3, 9, 9, 3, 7, 3, 1, 9, 4, 5, 6, 2, 5, 2, 6, 9, 4, 7, 5, 8, 5, 3, 3, 7, 2, 3, 3, 7, 9, 3, 5, 6, 8, 2, 7, 8, 2, 6, 5, 2, 7, 9, 1, 9, 9, 8, 8, 3, 1, 9, 7, 1, 6, 7, 6, 3, 4, 7, 9, 1, 2, 9, 3, 1, 7, 7, 9, 8, 6, 1, 5, 2, 5, 6, 6, 2, 3, 6, 7, 1, 8, 3, 3, 2, 6, 1, 7, 5, 3, 6, 4, 8, 7, 2, 3, 6, 8, 7, 9, 7, 4, 7, 1, 6, 7, 9, 9, 9, 9, 8, 3, 3, 6, 3, 8, 3, 2, 2, 5, 7, 9, 1, 2, 4, 4, 5, 7, 5, 6, 8, 8, 7, 3, 1, 4, 8, 7, 9, 2, 2, 9, 9, 2, 5, 8, 6, 4, 4, 7, 7, 7, 6, 1, 3, 5, 7, 1, 3, 9, 8, 5, 5, 5, 4, 8, 5, 2, 2, 5, 1, 3, 7, 9, 8, 8, 9, 9, 8, 5, 3, 8, 9, 6, 6, 1, 2, 3, 8, 7, 1, 4, 6, 6, 8, 7, 7, 1, 6, 2, 6, 4, 5, 9, 9, 9, 4, 3, 2, 8, 9, 4, 1, 6, 3, 2, 6, 7, 2, 7, 2, 5, 6, 5, 2, 5, 1, 7, 3, 9, 5, 3, 8, 6, 1, 5, 3, 4, 2, 4, 4, 9, 7, 9, 4, 6, 6, 5, 8, 7, 8, 9, 5, 4, 2, 9, 3, 9, 9, 1, 5, 9, 9, 2, 4, 9, 1, 6, 3, 6, 4, 4, 7, 6, 3, 1, 9, 5, 7, 3, 8, 9, 5, 5, 6, 6, 7, 9, 5, 3, 9, 3, 3, 6, 8, 4, 1, 1, 6, 7, 2, 3, 8, 7, 2, 6, 3, 6, 1, 5, 5, 8, 2, 1, 2, 8, 3, 7, 7, 6, 7, 6, 2, 9, 3, 6, 1, 2, 8, 9, 2, 7, 2, 3, 7, 6, 2, 2, 3, 7, 1, 9, 1, 1, 4, 6, 7, 1, 4, 2, 8, 6, 2, 3, 3, 5, 4, 3, 5, 1, 4, 4, 1, 1, 8, 1, 3, 3, 2, 3, 1, 9, 7, 9, 9, 5, 9, 5, 3, 8, 5, 4, 8, 7, 1, 6, 2, 8, 2, 2, 5, 3, 5, 8, 5, 4, 3, 5, 1, 4, 1, 5, 7, 8, 6, 7, 3, 7, 2, 2, 6, 5, 7, 1, 8, 7, 2, 4, 2, 7, 6, 9, 1, 1, 6, 9, 9, 5, 1, 4, 9, 7, 1, 4, 5, 8, 8, 4, 4, 8, 4, 9, 3, 4, 9, 7, 2, 6, 2, 7, 6, 3, 2, 9, 1, 3, 5, 1, 1, 8, 2, 4, 3, 1, 5, 5, 6, 9, 8, 2, 7, 1, 2, 1, 8, 8, 4, 4, 3, 4, 7, 3, 8, 7, 4, 5, 7, 3, 4, 3, 6, 5, 6, 4, 4, 6, 3, 8, 1, 7, 9, 9, 2, 9, 6, 8, 9, 3, 2, 2, 2, 2, 5, 6, 1, 9, 8, 4, 8, 4, 4, 6, 5, 8, 7, 3, 7, 1, 4, 3, 1, 1, 7, 7, 7, 9, 3, 7, 4, 2, 1, 1, 6, 1, 5, 8, 1, 7, 9, 8, 1, 8, 9, 5, 5, 4, 1, 4, 1, 4, 7, 4, 2, 3, 6, 2, 3, 9, 4, 4, 7, 6, 1, 2, 4, 2, 1, 8, 8, 3, 2, 3, 2, 1, 7, 3, 9, 1, 4, 1, 8, 3, 7, 3, 2, 1, 2, 6, 3, 3, 2, 8, 3, 8, 1, 9, 4, 6, 4, 8, 5, 8, 3, 4, 7, 2, 4, 1, 9, 1, 5, 4, 3, 6, 9, 9, 5, 2, 4, 7, 7, 4, 2, 2, 6, 6, 6, 3, 8, 9, 5, 1, 7, 5, 6, 9, 9, 4, 4, 4, 2, 8, 4, 6, 4, 6, 1, 7, 4, 5, 7, 1, 2, 4, 3, 6, 9, 3, 4, 9, 2, 4, 2, 4, 7, 9, 6, 1, 2, 4, 2, 2, 6, 7, 3, 2, 4, 1, 3, 6, 1, 7, 7, 7, 5, 7, 6, 4, 6, 6, 9, 4, 6, 6, 2, 2, 9, 3, 2, 2, 4, 3, 7, 2, 8, 5, 5, 1, 2, 7, 3, 2, 8, 4, 8, 3, 7, 9, 3, 4, 4, 9, 7, 5, 1, 1, 1, 1, 4, 3, 3, 4, 4, 2, 1, 4, 8, 6, 2, 6, 2, 2, 4, 4, 9, 8, 2, 9, 1, 4, 7, 3, 4, 4, 5, 2, 1, 1, 3, 9, 4, 6, 3, 6, 1, 2, 4, 5, 3, 7, 7, 3, 5, 1, 8, 4, 9, 8, 1, 5, 5, 8, 4, 8, 5, 5, 6, 9, 1, 7, 7, 8, 8, 9, 4, 7, 9, 8, 2, 1, 9, 8, 2, 2, 4, 6, 3, 2, 9, 8, 3, 8, 7, 7, 7, 1, 9, 2, 3, 3, 2, 9, 3, 3, 7, 6, 3, 4, 3, 9, 4, 6, 5, 4, 4, 3, 9, 4, 5, 8, 5, 6, 4, 2, 3, 3, 2, 5, 9, 4, 5, 1, 4, 5, 3, 3, 4, 5, 3, 1, 6, 7, 5, 3, 2, 4, 1, 4, 3, 8, 2, 6, 7, 7, 3, 9, 4, 3, 9, 2, 2, 5, 4, 9, 7, 5, 1, 5, 2, 7, 6, 5, 2, 2, 4, 2, 4, 4, 4, 1, 5, 3, 2, 4, 6, 2, 5, 4, 1, 5, 2, 8, 1, 9, 5, 7, 8, 2, 8, 1, 8, 3, 2, 6, 9, 1, 8, 5, 6, 2, 2, 4, 7, 2, 7, 8, 4, 9, 6, 4, 9, 5, 7, 6, 4, 4, 3, 5, 3, 8, 6, 6, 6, 7, 3, 8, 3, 5, 7, 7, 5, 4, 3, 3, 8, 5, 1, 8, 6, 8, 2, 7, 2, 6, 9, 7, 3, 2, 2, 6, 1, 2, 2, 3, 1, 5, 6, 8, 2, 4, 3, 5, 1, 1, 6, 4, 8, 4, 1, 6, 4, 8, 4, 2, 4, 5, 6, 4, 9, 2, 5, 1, 9, 8, 7, 8, 3, 6, 2, 5, 7, 2, 1, 3, 9, 6, 9, 8, 8, 9, 8, 4, 4, 8, 1, 5, 5, 8, 3, 9, 1, 8, 6, 6, 4, 8, 3, 9, 5, 5, 5, 3, 3, 9, 7, 2, 2, 1, 2, 1, 6, 4, 6, 9, 3, 8, 9, 8, 9, 5, 5, 4, 1, 2, 7, 1, 9, 1, 6, 1, 6, 4, 8, 4, 1, 1, 2, 7, 9, 1, 4, 9, 4, 1, 3, 4, 4, 3, 1, 9, 2, 8, 9, 6, 8, 6, 4, 2, 5, 8, 2, 1, 5, 4, 9, 8, 5, 4, 3, 8, 2, 7, 4, 5, 8, 4, 3, 8, 8, 7, 1, 3, 5, 5, 8, 7, 9, 3, 3, 6, 8, 9, 2, 7, 2, 1, 6, 7, 5, 9, 3, 7, 1, 1, 1, 9, 5, 2, 4, 7, 9, 1, 8, 3, 4, 9, 6, 9, 8, 2, 8, 2, 5, 1, 6, 3, 4, 5, 6, 2, 8, 2, 7, 4, 7, 6, 7, 8, 3, 6, 4, 6, 1, 2, 1, 3, 5, 5, 9, 6, 3, 7, 3, 5, 3, 3, 4, 4, 7, 7, 1, 9, 8, 6, 7, 3, 8, 4, 6, 6, 7, 5, 1, 6, 5, 7, 2, 2, 6, 2, 1, 2, 4, 2, 2, 5, 5, 8, 5, 6, 2, 3, 9, 7, 4, 2, 7, 8, 8, 3, 3, 9, 8, 1, 3, 6, 5, 4, 9, 4, 6, 2, 8, 6, 4, 6, 6, 1, 4, 5, 8, 8, 1, 1, 4, 1, 4, 7, 4, 7, 3, 5, 5, 9, 1, 3, 8, 8, 5, 3, 4, 5, 3, 1, 8, 9, 4, 4, 8, 6, 2, 4, 9, 7, 6, 7, 7, 4, 6, 4, 1, 9, 2, 2, 4, 6, 9, 1, 8, 3, 9, 4, 2, 8, 5, 7, 6, 9, 5, 9, 8, 6, 3, 7, 6, 4, 2, 8, 9, 4, 4, 8, 7, 6, 8, 5, 1, 4, 9, 7, 9, 1, 4, 4, 4, 3, 8, 7, 3, 5, 1, 3, 8, 6, 2, 3, 1, 9, 4, 8, 4, 1, 8, 1, 7, 8, 7, 5, 9, 3, 5, 7, 2, 9, 8, 7, 4, 4, 4, 6, 6, 9, 7, 6, 7, 9, 3, 9, 5, 2, 6, 2, 9, 4, 4, 2, 4, 5, 3, 1, 2, 6, 2, 9, 9, 9, 5, 6, 4, 9, 4, 8, 5, 7, 1, 1, 4, 2, 3, 4, 2, 7, 4, 1, 1, 2, 9, 8, 6, 2, 3, 1, 1, 3, 1, 1, 3, 1, 3, 1, 6, 6, 7, 9, 8, 3, 6, 3, 4, 4, 2, 7, 4, 5, 7, 9, 2, 8, 9, 6, 2, 2, 7, 6, 4, 2, 8, 8, 1, 8, 9, 3, 1, 3, 4, 4, 9, 8, 1, 5, 1, 5, 5, 2, 3, 2, 6, 6, 4, 7, 9, 3, 3, 6, 8, 9, 5, 9, 6, 5, 1, 6, 8, 5, 9, 3, 4, 2, 2, 4, 2, 2, 4, 4, 5, 8, 4, 7, 1, 4, 8, 1, 8, 7, 7, 3, 7, 9, 1, 5, 6, 7, 1, 8, 7, 3, 2, 2, 2, 1, 7, 1, 6, 4, 3, 4, 7, 8, 5, 2, 8, 4, 3, 7, 5, 1, 8, 7, 5, 9, 7, 9, 4, 1, 5, 1, 9, 8, 1, 6, 5, 6, 2, 7, 5, 3, 4, 2, 6, 3, 5, 2, 7, 8, 2, 8, 4, 1, 4, 5, 4, 9, 2, 1, 7, 2, 3, 4, 3, 2, 2, 3, 6, 1, 9, 3, 7, 7, 8, 5, 1, 8, 5, 1, 7, 4, 9, 9, 3, 2, 5, 6, 7, 5, 3, 4, 8, 3, 8, 7, 6, 3, 7, 8, 3, 3, 2, 5, 2, 1, 8, 2, 4, 5, 1, 5, 9, 7, 7, 1, 7, 3, 3, 9, 7, 5, 3, 5, 7, 8, 4, 2, 3, 6, 9, 2, 3, 6, 2, 9, 6, 3, 6, 7, 1, 3, 4, 6, 9, 1, 5, 1, 5, 2, 6, 3, 9, 9, 1, 4, 9, 5, 4, 8, 3, 2, 2, 8, 4, 9, 8, 3, 1, 4, 3, 1, 5, 2, 6, 2, 1, 9, 4, 7, 8, 6, 5, 3, 8, 6, 1, 7, 5, 4, 3, 6, 4, 1, 5, 5, 2, 7, 5, 8, 6, 5, 5, 1, 1, 6, 4, 3, 9, 2, 3, 2, 4, 9, 8, 5, 8, 5, 8, 9, 4, 6, 6, 1, 4, 2, 4, 7, 4, 7, 6, 3, 7, 7, 8, 4, 1, 3, 8, 2, 6, 8, 2, 9, 2, 2, 6, 6, 6, 3, 3, 9, 8, 4, 6, 7, 5, 6, 9, 5, 5, 5, 7, 4, 7, 2, 6, 7, 1, 9, 5, 1, 2, 9, 5, 2, 5, 1, 3, 8, 9, 1, 7, 5, 6, 1, 7, 8, 5, 4, 3, 6, 4, 4, 9, 8, 5, 5, 9, 3, 3, 9, 5, 1, 5, 3, 8, 9, 7, 3, 9, 9, 5, 8, 8, 1, 9, 5, 4, 5, 2, 1, 1, 2, 4, 7, 5, 3, 3, 6, 9, 2, 2, 3, 8, 9, 8, 3, 1, 2, 8, 4, 3, 7, 3, 4, 7, 7, 1, 5, 3, 2, 3, 4, 2, 3, 8, 3, 2, 8, 2, 9, 8, 7, 4, 2, 2, 3, 3, 4, 1, 9, 6, 5, 8, 5, 1, 2, 8, 5, 2, 6, 5, 2, 6, 3, 2, 4, 2, 9, 1, 7, 7, 7, 6, 8, 9, 6, 8, 9, 4, 9, 2, 3, 4, 6, 2, 3, 1, 7, 8, 6, 3, 3, 5, 8, 5, 1, 5, 5, 1, 4, 1, 3, 8, 7, 6, 8, 3, 4, 9, 6, 9, 8, 7, 8]).

drop(0, XS, XS).
drop(N, [], []) :- N > 0.
drop(N, [_|XS], A) :-
  N > 0,
  M is N - 1,
  drop(M, XS, A).

take(0, _, []).
take(N, [], []) :- N > 0.
take(N, [X|XS], [X|Rest]) :-
  N > 0,
  M is N - 1,
  take(M, XS, Rest).

rotate(N, XS, A) :-
  drop(N, XS, Tail),
  take(N, XS, Head),
  append(Tail, Head, A).

matchingPairs([], [], []).
matchingPairs([X | XS], [X | YS], [X | Rest]) :-
  matchingPairs(XS, YS, Rest).
matchingPairs([X | XS], [ Y | YS], Rest) :-
  X \= Y,
  matchingPairs(XS, YS, Rest).

halfLength(XS, Hl) :-
  length(XS, Len),
  Hlf is Len / 2,
  floor(Hlf, Hl).

sum_list([], 0).
sum_list([H|T], Sum) :-
  sum_list(T, Rest),
  Sum is H + Rest.

answer(A) :-
  input(Input),
  halfLength(Input, HalfLength),
  rotate(HalfLength, Input, Rotated),
  matchingPairs(Input, Rotated, Matches),
  sum_list(Matches, A).