using System;
 class ProgramC
    {
        static void Main(string[] args)
        {
            //まずは数字を読む

            string[] input = Console.ReadLine().Split(' ');
            int n = int.Parse(input[0]);
            int m = int.Parse(input[1]);

            int[] fallstair = new int[m + 1];
            long[] stair = new long[n + 1];

            //とりあえず全部読みこむ
            for (int i = 0; i <m;i++)
                fallstair[i] = int.Parse(Console.ReadLine());

            //ない階段を数える
            int count = 0;

            //結果出力
            long output = 0;

            //初期条件設定
            if (m >= 2)
            {
                if (fallstair[count] == 1 && fallstair[count + 1] == 2)
                {
                    output = 0;
                    goto end;
                }
                else if (fallstair[count] == 1 && fallstair[count + 1] != 2)
                {
                    stair[0] = 0;
                    stair[1] = 1;
                    count++;
                }
                else if (fallstair[count] == 2)
                {
                    stair[0] = 1;
                    stair[1] = 0;
                    count++;
                }
                else
                {
                    stair[0] = 1;
                    stair[1] = 2;

                }
            }
            else if(m == 1)
            {
                if (fallstair[count] == 1)
                {
                    stair[0] = 0;
                    stair[1] = 1;
                    count++;
                }
                else if (fallstair[count] == 2)
                {
                    stair[0] = 1;
                    stair[1] = 0;
                    count++;
                }
                else
                {
                    stair[0] = 1;
                    stair[1] = 2;

                }
            }

            for (int i = 2; i < n; i++)
            {
                int fall = fallstair[count];

                if (fall == i + 1)
                {
                    stair[i] = 0;
                    count++;
                }
                else
                    stair[i] = stair[i - 1] + stair[i - 2];

                //ダメなときは出す
                if (stair[i] == 0 && stair[i - 1] == 0)
                {
                    output = 0;
                    goto end;
                }

                if (stair[i] > 1000000007)
                    stair[i] %= 1000000007;

            }

            output = stair[n - 1];

            //普通に終われば普通に出す


            
            //最初からダメなら求めない
            end:

            ;

            Console.WriteLine(output);


        }
    }