#include <bits/stdc++.h>
#include <boost/range/adaptors.hpp>
#include <boost/multiprecision/cpp_int.hpp>

/***** type *****/
using namespace std;
using ll = long long;
using ld = long double;
template <class T> using vt = vector<T>;
template <class T> using vvt = vector<vector<T>>;
template <class T> using vvvt = vector<vector<vector<T>>>;
using ml = boost::multiprecision::cpp_int;

/***** define *****/
#define all(c) (c).begin(), (c).end()            // begin to end
#define rep(i, b, e) for (ll i = b; i < e; i++)  // repeat
#define repr(i, b, e) for (ll i = b; e < i; i--) // repeat reverse
/***** const value *****/
#define llong_max 9223372036854775807            // 9 * 10^18
#define ldbl_max 1.79769e+308                    // 1.7 * 10^308
#define mod 1000000007                           // 1e9 + 7
#define pi 3.14159265                            // 3.14 ...
/***** for each macro *****/
#define fori(i, ...) if(ll i = -1) for(__VA_ARGS__) if(i++, true)
#define each(i, e, v) fori(i, auto& e: v)
#define forir(i, ...) if(ll i = Size(v)) for(__VA_ARGS__) if(i--, true)
#define eachr(i, e, v) forir(i, auto& e: boost::adaptors::reverse(v))

/***** lambda *****/
auto Bit = [] // long long bit shift
(auto n) { return (1LL << n); };
auto Count = [] // long long count value
(auto b, auto e, auto x) { return (ll)count(b, e, x); };
auto CtoLL = []  // char to long long
(auto c) { return (ll)(c - '0'); };
auto Divc = []  // long double div ceiling
(auto a, auto b) { return ceil((ld)a / (ld)b); };
auto Modify = [] // add vector or sub vector
(auto b, auto e, auto x)
{ for(auto it = b; it != e; ++it) *it += x; };
auto Size = []  // long long collection size
(auto& c) { return (ll)(c).size(); };
auto Sum = []   // long long accumulate
(auto b, auto e) { return accumulate(b, e, 0LL); };
auto VVT = []   // vector<vector<T>> resize 
(auto& vvt, auto ysize, auto xsize)
{ vvt.resize(ysize); each(i, vy, vvt) vy.resize(xsize); };
auto VVVT = []   // vector<vector<vector<T>>> resize 
(auto& vvvt, auto zsize, auto ysize, auto xsize)
{ vvvt.resize(zsize); each(z, vz, vvvt) VVT(vz, ysize, xsize); };
auto InVVT = []  // input vector<vector<T>> (T != struct)
(auto& vvt) { each(y, vy, vvt) each(x, e, vy) cin >> e; };
auto InVVVT = [] // input vector<vector<vector<T>>> (T != struct)
(auto& vvvt) { each(z, vz, vvvt) InVVT(vz); };

namespace NyaGadget
{
	/*** MOD ライブラリ ***/

	template<ll maxv> struct ModLL
	{
		ll x;

		// コンストラクタ
		ModLL() { x = 0; }
		ModLL(ll x_)
		{
			x = x_ % maxv + maxv;
			if (x >= maxv)
				x -= maxv;
		}

		// 符号
		ModLL operator + () const { return x; }
		ModLL operator - () const { return (-x < 0) ? maxv - x : -x; }

		// 加減乗除演算子
		ModLL& operator += (ModLL r)
		{
			if ((x += r.x) >= maxv)
				x -= maxv;
			return *this;
		}
		ModLL& operator -= (ModLL r)
		{
			if ((x -= r.x) < 0)
				x += maxv;
			return *this;
		}
		ModLL& operator *= (ModLL r)
		{
			x = (unsigned long long) x * r.x % maxv;
			return *this;
		}
		ModLL& operator /= (ModLL r)
		{
			x = x * Inv(r.x, maxv) % maxv;
			return *this;
		}

		ModLL operator + (ModLL r) const { return ModLL(*this) += r; }
		ModLL operator - (ModLL r) const { return ModLL(*this) -= r; }
		ModLL operator * (ModLL r) const { return ModLL(*this) *= r; }
		ModLL operator / (ModLL r) const { return ModLL(*this) /= r; }

		// 逆元 x^{-1} (主に除算演算子で使用)
		ll Inv(ll a, ll m)
		{
			ll b = m, u = 1, v = 0;

			while (b)
			{
				ll t = a / b;
				a -= t * b; swap(a, b);
				u -= t * v; swap(u, v);
			}

			u %= m;

			return (u < 0) ? u + m : u;
		}

		// 比較演算子
		bool operator == (ModLL& r) const { return x == r.x; }
		bool operator != (ModLL& r) const { return x != r.x; }
		bool operator <  (ModLL& r) const { return x < r.x; }
		bool operator <= (ModLL& r) const { return x <= r.x; }
		bool operator >  (ModLL& r) const { return x > r.x; }
		bool operator >= (ModLL& r) const { return x >= r.x; }

		// 入出力演算子
		friend ostream& operator << (ostream& s, ModLL<maxv> a)
		{
			s << a.x;
			return s;
		}
		friend istream& operator >> (istream& s, ModLL<maxv>& a)
		{
			s >> a.x;
			return s;
		}
	};
}

using namespace NyaGadget;
using mll = ModLL<1000000007>;

int main(void)
{
	ll N, M; cin >> N >> M;
	vt<bool> hole_exist(N, false);
	rep(i, 0, M)
	{
		ll x; cin >> x;
		hole_exist[x] = true;
	}

	vt<mll> dp(N+1);
	dp[0] = 1;
	if (!hole_exist[1]) dp[1] = 1;
	rep(i, 2, N+1)
	{
		if (!hole_exist[i-1]) dp[i] += dp[i - 1];
		if (!hole_exist[i-2]) dp[i] += dp[i - 2];

		if (hole_exist[i-1] && hole_exist[i-2])
		{
			cout << 0;
			return 0;
		}
	}

	cout << dp[N];
	return 0;
}



Measured memory_bytes: 1024