How to Auto Generate Numbers Based On Accounting Year

Auto Generate Number Based on Accounting Year
Hi, 
I would like to auto generate number based on accounting year April to March
Say
K-001/14-15
K-002/14-15
Here K-001, K-002 is auto generate number 14-15 is Accounting year.
The Auto generate number should get reset when accounting year start 15-16.
Please help me