let f a b =
    let pc = [ 23 .. 25 ]
    let travel = [ a .. b]
    let ng = travel |> List.where(fun x -> List.contains x pc) |> List.length
    3 - ng

let A, B = let t = stdin.ReadLine().Split() |> Array.map int in t.[0], t.[1]

f A B
|> printfn "%i"