How to make a command that only effects players in a certain gamemode

Question

As of right now I have

/gamemode adventure @a [r=40, name=!"contract to kil"]

Which update other players gamemode but it continue to do so until lagging, I want it to exclude players already in adventure to prevent lag.

I've tried adding:

[gamemode=!adventure]

but it doesn't work

Answer 1

Problem solved, I was looking for another solution to a different problem and stumbled upon the answer M=2 is adventure So I plugged in m=!2 Which stopped the constant updating and lagging, stress relieved...