The blue boxes below should be in numeric order and form a "B". (Boxes labelled "A" should be in the first column; boxes labelled "B" should be in the second; arrows indicate the correct alignment.)
⇦ A 1
⇦ B 2
⇦ A 3
B 4 ⇨
⇦ A 5
B 6 ⇨
⇦ A 7
⇦ B 8
⇦ A 9
B 10 ⇨
⇦ A 11
B 12 ⇨
⇦ A 13
⇦ B 14