// http://yukicoder.me/problems/34
open System

let dprintfn fmt = Printf.kprintf Diagnostics.Debug.WriteLine fmt

let primes n =
    let mid = float n |> sqrt |> floor |> int
    let table = Array.init (n+1) (fun _ -> true)
    seq {
        for i in 2 .. mid do
            if table.[i] then
                yield i
                for j in (i+i) .. i .. n do
                    table.[j] <- false
        for i in (mid+1) .. n do
            if table.[i] then
                yield i
    }

let encode x =
    let rec loop acc n =
        let m = n % 10
        let acc = Set.add m acc
        let d = n / 10
        if d = 0 then acc 
        else loop acc d
    loop Set.empty x

[<EntryPoint>]
let main argv = 
    let max_N = 5000000
    let N = Console.ReadLine().Trim() |> int
    let A = Console.ReadLine().Trim().Split([|' '|]) |> Array.map int |> Set.ofArray
    primes max_N
    |> Seq.fold (fun (start, rest, ans) x ->
                 let X = encode x
                 if Set.difference X A = Set.empty then (start, Set.difference rest X, ans)
                 else 
                    let ans =
                        if rest = Set.empty && ans < x-1-start then x-1-start else ans
                    let start = x+1
                    let rest = A
                    (start, rest, ans)
                ) (1, A ,-1)
    |> fun (start, rest, ans) ->
        let ans = 
            if rest = Set.empty && ans < max_N - start then max_N - start 
            else ans
        printfn "%d" ans
    0