let solve n =

  let inline primeFactor n =
      let zero = LanguagePrimitives.GenericZero
      let one  = LanguagePrimitives.GenericOne
      let two  = one + one
      let rec f num divisor acc =
          if divisor = num then
              divisor :: acc
          elif num % divisor = zero then
              f (num / divisor) divisor (divisor :: acc)
          else
              f num (divisor + one) acc
      f n two []
  
  [(max (n-100) 4) .. n+100]
  |> List.find (fun x -> (primeFactor x |> List.length) > 1)

let N = stdin.ReadLine() |> int

solve N
|> stdout.WriteLine