using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            new Program().Solve(new ConsoleInput(Console.In, ' '));
        }

        public void Solve(ConsoleInput cin)
        {
            var N = cin.ReadInt;
            var M = cin.ReadInt;
            var a = new int[N+1];
            var dp = new long[N+1];

            for (int i = 0; i < M; i++)
            {
                a[cin.ReadInt] = 1;
            }

            dp[0] = 1;
            for (int i = 0; i < N; i++)
            {
                for (int j = i+1; j <= Min(N,i + 2); j++)
                {
                    if (a[j] == 0) 
                    {
                        dp[j] += dp[i];
                        dp[j] %= 1000000007;
                    }
                }
            }

            var ans = dp[N];
            WriteLine(ans);
        }

        public int GetMod(int num) 
        {
            var mod = 1000000007;
            var result = num % mod;
            if (result < 0) result += mod;
            return result;
        }

        public void Display(char[] array)
        {
            var txt = "";
            foreach (var item in array)
            {
                txt += " " + item;
            }
            WriteLine("{0}", txt);
        }

        public void Display(int[] array)
        {
            var txt = "";
            foreach (var item in array)
            {
                txt += " " + item.ToString();
            }
            WriteLine("{0}", txt);
        }

        public void Display(int index,int[] array)
        {
            var txt = "";
            foreach (var item in array)
            {
                txt += " " + item.ToString();
            }
            WriteLine("{0} : {1}", index,txt);
        }

        public void Display(List<int>[] list) 
        {
            for (int i = 0; i < list.Length; i++)
            {
                Display(i, list[i].ToArray());
            }
        }
    }

    public class ConsoleInput
    {
        private readonly System.IO.TextReader _stream;
        private char _separator = ' ';
        private Queue<string> inputStream;
        public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
        {
            this._separator = separator;
            this._stream = stream;
            inputStream = new Queue<string>();
        }

        public string Read
        {
            get
            {
                if (inputStream.Count != 0) return inputStream.Dequeue();
                string[] tmp = _stream.ReadLine().Split(_separator);
                for (int i = 0; i < tmp.Length; i++)
                    inputStream.Enqueue(tmp[i]);
                return inputStream.Dequeue();
            }
        }

        public string ReadLine { get { return _stream.ReadLine(); } }
        public int ReadInt { get { return int.Parse(Read); } }
        public long ReadLong { get { return long.Parse(Read); } }
        public double ReadDouble { get { return double.Parse(Read); } }
        public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
        public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
        public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
    }
}


Measured memory_bytes: 34604