Let me give you an example.

Beginning: 3* 1=3.

The price difference between the middle 3*2=6 and the beginning is 3, that is, the stock value is 3 when buying. Now, due to various reasons, his valuation has risen to 6, that is, the spread of one share is +3, so this +3 3 is the net inflow.

Similarly, we can see a net outflow.

I hope it can help you understand effectively.