Scanf.scanf "%d %d" (fun a b ->
    Printf.printf "%d\n" @@
    (if a <= 23 && 23 <= b then 0 else 1) + 
    (if a <= 24 && 24 <= b then 0 else 1) + 
    (if a <= 25 && 25 <= b then 0 else 1)
)