negative itc because of purchase return.

Example.
ITC on puchases in the month of june 2019 is - CGST-1000 AND SGST-1000. BUT Purchase return(goods purchased in the previous month) ITC reversal is CGST-1200 AND SGST-1200.
SO The net ITC is negative cgst 200 and sgst 200.
query- How to show negative itc in Gstr 3B. plz suggest with provisions (if any)