Answer:
One
Step-by-step explanation:
There are five accidentals, the sharps and flats, but each note can only be affected by one accidental at a time. So you can have F# and Ab and C# but not something like F#b or something weird like that.
A sharp raises a note by a half step. Instead of the original note, you should play the note that is a half step above. A flat lowers a note by a half step. Instead of the original note, you should play the note that is a half step below.
Hope this helps :)
Stay cold,
Brook