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


namespace AtCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            var cin = new Scanner();
            var N = cin.nextInt();
            var M = cin.nextInt();
            ulong mod = 1000000007;
            
            int[] a = new int[M];
            bool[] breakStairs = new bool[N+100];
            if (M != 0)
            {
                for (int i = 0; i < M; i++)
                {
                    a[i] = cin.nextInt();
                }

                for (int i = 0; i < M; i++)
                {
                    breakStairs[a[i]] = true;
                }


            }

            ulong[] dp = new ulong[N + 100];
            dp[0] = 1;
            // 遷移式
            for(int now = 0; now < N; ++now)
            {
                for(int next = now+1; next <= Math.Min(N,now+2); ++next)
                {
                    if (!breakStairs[next])
                    {
                        dp[next] += dp[now];
                        dp[next] %= mod;
                    }
                }
            }
            Console.WriteLine(dp[N]);
        }

        // 最小公倍数
        static long Lcm(long a, long b)
        {
            return a * (b / Gcd(a, b));
        }

        // 最大公約数
        static long Gcd(long a, long b)
        {
            if (a < b)
                return Gcd(b, a);
            long d = 0;
            do
            {
                d = a % b;
                a = b;
                b = d;
            } while (d != 0);
            return a;
        }
    }

    class Point
    {
        public int x { get; set; }
        public int y { get; set; }
    }


    class Scanner
    {
        string[] s;
        int i;

        char[] cs = new char[] { ' ' };

        public Scanner()
        {
            s = new string[0];
            i = 0;
        }

        public string next()
        {
            if (i < s.Length) return s[i++];
            string st = Console.ReadLine();
            while (st == "") st = Console.ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            if (s.Length == 0) return next();
            i = 0;
            return s[i++];
        }

        public int nextInt()
        {
            return int.Parse(next());
        }
        public int[] ArrayInt(int N, int add = 0)
        {
            int[] Array = new int[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextInt() + add;
            }
            return Array;
        }

        public long nextLong()
        {
            return long.Parse(next());
        }

        public long[] ArrayLong(int N, long add = 0)
        {
            long[] Array = new long[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextLong() + add;
            }
            return Array;
        }

        public double nextDouble()
        {
            return double.Parse(next());
        }


        public double[] ArrayDouble(int N, double add = 0)
        {
            double[] Array = new double[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextDouble() + add;
            }
            return Array;
        }
    }
}

Measured memory_bytes: 18388