program strings_with

 implicit none
 integer::n,i
 character::s*100,t*100,ans*200,ss,tt
 
 read*,n
 read*,s,t
 print*,s,t

 ss=trim(s)
 tt=trim(t)

 do i=1,n 
  ans(2*(i-1):2*(i-1))=ss(i:i)
  ans(2*i:2*i)=tt(i:i)
 end do
 
 print*,trim(ans)

end program strings_with
