You have blocks 1, 2, 3, and 4.
Post the first lines of block 1 and 2 together, then enter.
Lines 2 of blocks 1 and 2 together, then enter.
Lines 3 of blocks 1 and 2 together, then enter.
Lines 4 of blocks 1 and 2 together, then enter.
Lines 1 of blocks 3 and 4 together, then enter.
Lines 2 of blocks 3 and 4 together, then enter.
Lines 3 of blocks 3 and 4 together, then enter.
Lines 4 of blocks 3 and 4 together, then enter.