program bbb

implicit none
integer :: n, i, j
character(200) :: s, t, st

read*, n
read*, s, t
do i = 1, 200
st(i:i) = ' '
end do
s = trim(s)
t = trim(t)

j = 0
do i = 1, n
j = j + 1
st(j:j) = s(i:i)
j = j + 1
st(j:j) = t(i:i)
end do

write(*,*) trim(st)

end program