program main
  implicit none
  character(100000) :: s
  character(50000) :: odd
  integer :: i, j
  read(*, *) s
  do i = 1, len(s), 2
    j = (i + 1) / 2
    odd(j:j) = s(i:i)
  end do
  write(*, "(a)") trim(odd)
end program main
