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



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

        val ans = List.foldl (fn (x, minAcc) =>
                                 Int.min(minAcc, x*a + (d-x)*b))
                             ((a + b) * d)
                             (List.tabulate (d + 1, fn i => i))              
    in
        print (Int.toString ans ^ "\n")
    end