How to get difference of last() and first() values in the influx measurement

I have grafana setup with influx. I can run some general queries in the influx console which i’m finding hard to mimic the same in grafana.

Influx Query : select last(count) - first(count) as Count from measurement1

In grafana i’m able to select last() or first() with ease and not getting how to get the difference of it.
Grafana Version - 6.4.0


Does spread() influxql function give you want you need?