using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("6 1");
            WillReturn.Add("3");
            //4
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("10 2");
            WillReturn.Add("4");
            WillReturn.Add("5");
            //0
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("100 5");
            WillReturn.Add("1");
            WillReturn.Add("23");
            WillReturn.Add("45");
            WillReturn.Add("67");
            WillReturn.Add("89");
            //608200469
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();

        int[] wkArr = InputList[0].Split(' ').Select(X => int.Parse(X)).ToArray();
        int N = wkArr[0];

        var AArr = new List<int>();
        foreach (string EachStr in InputList.Skip(1)) {
            AArr.Add(int.Parse(EachStr));
        }

        //場合の数[現在位置]なDP表
        int[] DPArr = new int[N + 1];
        DPArr[0] = 1;
        int UB = N;

        for (int I = 0; I <= UB; I++) {
            int NextDan;

            //1段あがる場合
            NextDan = I + 1;
            if (NextDan <= UB && AArr.IndexOf(NextDan) == -1) {
                DPArr[NextDan] = DPArr[NextDan] + DPArr[I];
                DPArr[NextDan] %= 1000000007;
            }

            //2段あがる場合
            NextDan = I + 2;
            if (NextDan <= UB && AArr.IndexOf(NextDan) == -1) {
                DPArr[NextDan] = DPArr[NextDan] + DPArr[I];
                DPArr[NextDan] %= 1000000007;
            }
        }
        Console.WriteLine(DPArr[UB]);
    }
}
