If Value is less than 0 do not display negative value


I am having 2 different metrics and i am doing a difference of these metrics and its getting plotted in pie chart. I am using Prometheus as datasource.

eg: round(sum(increase(metrics1)[_range])) -on() round(sum(increase(metrics2)[_range]))

And some point i am getting values as -1, -9. I do not want to display negative values. I just want to display 0 as value.

How can i resolve this issue?