This is a trick question
There are 4 required
signs at a stairwell
1 - Corridor - The stairwell evacuation. (min. 12" x 12") FIRE SAFETY - TITLE 19
2 - Corridor - Stairwell ADA
sign (usually saying "EXIT STAIR DOWN") with tactile and braille - BUILDING CODE - TITLE 24
3 - Interior - ADA Floor ID (By Door) - BUILDING CODE - TITLE 24
4 - Interior - Floor Designation
Sign (at landing on wall) (Min. 12" x 18" with 1" and 5" copy height requirement) - FIRE SAFETY - TITLE 19