I need help with circuits to balance chests.

I have input from left, into chest 1 which inputs into chest 2, into 3, into 4.

I need a circuit that will read between chest 1 and 2 and if 2 has less that 1 will run the inserter. If 3 has less than 2 it will run the inserter. If 4 has less than 3 it ...