Amber Company uses two producing departments (A and B) and two service departments (S1 and S2). The costs incurred in S1 and S2 are allocated to Departments A and B and included in their factory overhead rates for costing products. S1 costs are allocated based on the number of employees, S2 costs are allocated based on direct labor-hours, and the production departmental overhead rates are also based on direct labor-hours. The following data are available for a recent period:

S1

S2

A

B

Direct department costs

$24,000

$36,000

$70,000

$117,500

Number of employees

1

2

16

9

Direct labor hours

225

150

1,125

900

What is the order of allocation under the step cost allocation method?