integer::N
  integer,allocatable::num(:,:)
  integer::dim,itr,offset
  character*32::cformat='(i0.3,  i4.3)'
  read*,N
  allocate(num(N,N))

  ! even
  offset = 0
  do itr=1,N/2
     dim = N-itr*2+1
     do i=itr, itr+dim-1
        num(i,itr) = offset+i
     end do
     offset = offset + dim
     do i=itr, itr+dim-1
        num(N-itr+1,i) = offset + i
     end do
     offset = offset + dim
     do i=itr, itr+dim-1
        num(N-i+1,N-itr+1) = offset + i
     end do
     offset = offset + dim
     do i=itr, itr+dim-1
        num(itr,N-i+1) = offset + i
     end do
     offset=offset + dim - 1
  end do

  if ( mod(N,2) .eq. 1) then
     num(N/2+1,N/2+1)=N*N
  end if

  write (cformat(7:8),'(i2)') N-1
  print cformat,num
end program