yes, and it has to be put on the left border of where it needs to go

Look at [0, x, 0, 1]
If you want to pop x to the right place, you MUST pop 0, 1 at first.
It should spent extra two steps.

[[0, 1, 0, 1], [1, 0, 1, 2], [0]] 

step 1:
[[0, 1, 0], [1, 1, 0, 1, 2], [0]] 

step 2:
[[0, 1, 0], [1, 1, 0, 1], [2, 0]] 

step 3:
[[0, 0, 1, 0], [1, 1, 0, 1], [2]] 

step 4:
[[0, 0, 0, 1], [1, 1, 0, 1], [2]] 

step 5:
[[0, 0, 0], [1, 1, 1, 0, 1], [2]] 

step 6:
[[0, 0, 0], [1, 1, 1, 1, 0], [2]] 

step 7:
[[0, 0, 0, 0], [1, 1, 1, 1], [2]]