using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp86 {
    class Program {
        static void Main(string[] args) {
            var st = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int N = st[0];
            int M = st[1];
            int mod = 1000000007;

            var a = new int[M + 2];
            a[0] = -1;
            for (int i = 1; i <= M; i++) {
                a[i] = int.Parse(Console.ReadLine());
            }
            a[M + 1] = N + 1;

            var X = new int[N];
            X[0] = 1;
            X[1] = 1;
            for (int i = 2; i < N; i++) {
                X[i] = (X[i - 2] % mod + X[i - 1] % mod) % mod;
            }

            //Console.WriteLine("Xの配列は" + string.Join(" ", X));
            //Console.WriteLine("aの配列は" + string.Join(" ", a));

            long ans = 1;

            for (int i = 1; i <= M + 1; i++) {
                //Console.WriteLine("X[" + (a[i] - a[i - 1] - 1) + "] = " + X[a[i] - a[i - 1] - 1] + "を掛けました");

                if (a[i] - a[i - 1] >= 2) {
                    ans *= X[a[i] - a[i - 1] - 2];
                    ans %= mod;
                }
                
                if (i != 1 && a[i] - a[i - 1] == 1) {
                    ans *= 0;
                }
            }

            Console.WriteLine(ans);
        }
    }
}
