var
  arr: array of integer;
  i: integer;
  f: text;

begin
  Assign(f, 'Input.txt');
  Reset(f);
  i := 0;
  while not Eof(f) do
  begin
    i += 1;
    SetLength(arr, i);
    Read(f, arr[i - 1]);
  end;
  Close(F);
  var sum := 0;
  var m := -1;
  i := 0;
  while i < High(arr) do
  begin
    m *= -1;
    sum += (((i + 1) * arr[i] * (i + 2) * arr[i + 1])) * m;
    i += 2;
  end;
  WriteLn(sum);
end.