fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)


fun member x nil = false
  | member x (h::tl) =
    if x = h
    then true
    else member x tl


val () =
    let
        val a = readInt ()
        val b = readInt ()

        val travelPeriod = List.tabulate (b - a + 1, (fn x => a + x))

        val ans =
            List.length
                (List.filter
                     (fn x =>
                         member x travelPeriod = false)
                     [23, 24, 25])
    in
        print (Int.toString ans ^ "\n")
    end