I have a following scenario for which I would like to know the average price of my shares.

Scenario:

Day 1: I brought say 500 shares @ Rs. 50/-

Lets say a week after that I feel that this share is going to be at downside today so I thought of selling my shares.

Day 7 (10:00 am) : I sold all 500 shares @ 48/-

Day 7 (3:00 pm) : I brought back all 500 shares @ 45/-

(Basically I did intraday short on Day 7)

My question is what would be avg. cost of my shares on Day 8 ?