Configure the Indicator widget as follows:

1. Configure general parameters (see General widget settings).
   

2. Enter the initial value of the widget (1).

3. Select a math operation to be performed with each dependent Counter widget (2-3).

   In the example on the image above, the widget counts the number of people without a mask: the initial value 0 (1) is added to the number of detected faces (2), and the number of detected faces in a mask is subtracted (3).

   
   

4. Configure other parameters in the same way as in the Counter widget (see Specifics of Counter widget configuration).
5. Click Save.