program strings_with_the_same_length
  implicit none
  integer :: n, i
  character(100) :: s, t
  read(*,*) n
  read(*,*) s, t
  do i = 1, n
    write(*,'(a)',advance='no') s(i:i)//t(i:i)
  end do
  write(*,*)
end program strings_with_the_same_length