
open System.Collections.Generic

type Scanner() = class
    let mutable hold = [||]
    let mutable index = 0
    member public this.Next() =
        if hold.Length > index
        then 
            index <- index + 1
            hold.[index - 1]
        else
            let mutable st = stdin.ReadLine()
            while st = "" do st <- stdin.ReadLine()
            hold <- st.Split(' ')
            if hold.Length = 0
            then
                this.Next()
            else
                index <- 1
                hold.[index - 1]
            
    member public this.NextI32() =
        this.Next() |> int

    member public this.ArrayI32(n: int) =
        [|for _ in 0 .. n - 1 -> this.NextI32()|]

    member public this.IArrayI32(n: int) =
        [|for i in 0 .. n - 1 -> this.NextI32(), i|]

    member public this.NextI64() =
        this.Next() |> int64
    
    member public this.ArrayI64(n: int) =
        [|for _ in 0 .. n - 1 -> this.NextI64()|]

    member public this.IArrayI64(n: int) =
        [|for i in 0 .. n - 1 -> this.NextI64(), i|]

    member public this.NextF32() =
        this.Next() |> float32
    
    member public this.ArrayF32(n: int) =
        [|for _ in 0 .. n - 1 -> this.NextF32()|]

    member public this.IArrayF32(n: int) =
        [|for i in 0 .. n - 1 -> this.NextF32(), i|]

    member public this.NextF64() =
        this.Next() |> double
    
    member public this.ArrayF64(n: int) =
        [|for _ in 0 .. n - 1 -> this.NextF64()|]

    member public this.IArrayF64(n: int) =
        [|for i in 0 .. n - 1 -> this.NextF64(), i|]

    member public __.Tuple2Array n (f : int -> 'a list) =
        [|for _ in 0 .. n - 1 -> f 2 |> fun x -> x.[0], x.[1]|]
    
    member public __.Tuple3Array n (f : int -> 'a list) =
        [|for _ in 0 .. n - 1 -> f 3 |> fun x -> x.[0], x.[1], x.[2]|]

    member public __.CountDic n (f : unit -> 'a) =
        let seqs = seq {for _ in 0 .. n - 1 -> f()}
        let dic = new Dictionary<'a, int64>();
        for i in seqs do
            if dic.ContainsKey(i)
            then dic.[i] <- dic.[i] + 1L
            else dic.Add(i, 1L)
        dic

end

[<EntryPoint>]
let main _ =
#if DEBUG
    printfn "debuged"
#endif

    let scanner = Scanner()
    let n = scanner.NextI32()
    let m = scanner.NextI32()
    let arr = scanner.ArrayI32(m)
    let flgArr = Array.create (n + 1) false
    arr |> Array.iter (fun x -> flgArr.[x] <- true)

    let f2 a = a % 1000000007L

    let f a b i =
        if flgArr.[i] then
            b, 0L
        else
            b, f2 (a + b)
    
    seq {1..n} |> Seq.fold (fun (a, b) x -> f a b x) (1L, 1L) |> snd
    |> printfn "%i"

    0
