using System;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using static System.Math;
using Debug = System.Diagnostics.Debug;
using MethodImplOptions = System.Runtime.CompilerServices.MethodImplOptions;
using MethodImplAttribute = System.Runtime.CompilerServices.MethodImplAttribute;

static class P
{
    static void Main()
    {
        //var nm = Console.ReadLine().Split().Select(int.Parse).ToArray();
        //var a = Enumerable.Repeat(0, nm[1]).Select(_ => int.Parse(Console.ReadLine().Trim())).ToList();
        var n = Read();
        var m = Read();
        var a = new List<int>();
        for (int i = 0; i < m; i++) a.Add(Read());
        ModInt prev2 = 0;
        ModInt prev = 1;
        for (int i = 1; i <= n; i++)
        {
            ModInt current = 0;
            if (0 <= a.BinarySearch(i))
            {
                current = 0;
            }
            else
            {
                current = prev + prev2;
            }
            prev2 = prev;
            prev = current;
        }
        Console.WriteLine(prev);
    }


    static readonly TextReader In = Console.In;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    static int Read()
    {
        int res = 0;
        int next = In.Read();
        while (48 > next || next > 57) next = In.Read();
        while (48 <= next && next <= 57)
        {
            res = res * 10 + next - 48;
            next = In.Read();
        }
        return res;
    }
}


struct ModInt
{
    const int MOD = 1000000007;
    long Data;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public ModInt(long data) { if ((Data = data % MOD) < 0) Data += MOD; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static implicit operator long(ModInt modInt) => modInt.Data;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static implicit operator ModInt(long val) => new ModInt(val);
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator +(ModInt a, ModInt b)
    {
        long res = a.Data + b.Data;
        return new ModInt() { Data = res >= MOD ? res - MOD : res };
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator +(ModInt a, long b) => a.Data + b;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator -(ModInt a, ModInt b)
    {
        long res = a.Data - b.Data;
        return new ModInt() { Data = res < 0 ? res + MOD : res };
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator -(ModInt a, long b) => a.Data - b;
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator *(ModInt a, ModInt b) => new ModInt() { Data = a.Data * b.Data % MOD };
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static ModInt operator /(ModInt a, ModInt b) => a.Data * GetInverse(b);

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public override string ToString() => Data.ToString();

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    static long GetInverse(long a)
    {
        long div;
        long p = MOD;
        long x1 = 1, y1 = 0, x2 = 0, y2 = 1;
        while (true)
        {
            if (p == 1) return x2;
            div = a / p;
            x1 -= x2 * div;
            y1 -= y2 * div;
            a %= p;
            if (a == 1) return x1;
            div = p / a;
            x2 -= x1 * div;
            y2 -= y1 * div;
            p %= a;
        }
    }
}


Measured memory_bytes: 13252