#include <bits/stdc++.h>
#define ll long long
#define MODV 1000000007
#define INF INT_MAX // 2147483647
#define INFLL LLONG_MAX // 9223372036854775807
#define rep(i, n) for(ll i=0, i##_len=(ll)(n); i<i##_len; i++)
#define repf(i, n) for(ll i=1, i##_len=(ll)(n+1); i<i##_len; i++)
#define per(i, n) for(ll i=((ll)(n))-1; i>=0; i--)
#define perf(i, n) for(ll i=((ll)(n)); i>0; i--)
#define all(v) v.begin(), v.end()
#define endl "\n"
#define vi vector<ll>
#define vvi vector<vector<ll>>
#define Yes() cout << "Yes" << endl
#define YES() cout << "YES" << endl
#define No() cout << "No" << endl
#define NO() cout << "NO" << endl
template<class T>bool chmax(T &a, const T &b){ if(a<b){ a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b){ if(b<a){ a=b; return 1; } return 0; }
using namespace std;

template<int MOD> struct Fp{
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD){ if(val<0) v += MOD; }
    constexpr int getmod(){ return MOD; }
    constexpr Fp operator - () const noexcept{ return val ? MOD - val : 0; }
    constexpr Fp operator + (const Fp& r) const noexcept{ return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept{ return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept{ return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept{ return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept{ val += r.val; if(val>=MOD) val -= MOD; return *this; }
    constexpr Fp& operator -= (const Fp& r) noexcept{ val -= r.val; if(val<0) val += MOD; return *this; }
    constexpr Fp& operator *= (const Fp& r) noexcept{ val = val*r.val%MOD; return *this; }
    constexpr Fp& operator /= (const Fp& r) noexcept{
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) { long long t = a/b; a -= t*b; swap(a, b); u -= t*v; swap(u, v); }
        val = val*u%MOD; if(val<0) val += MOD; return *this; }
    constexpr bool operator == (const Fp& r) const noexcept{ return this->val == r.val; }
    constexpr bool operator != (const Fp& r) const noexcept{ return this->val != r.val; }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept{ return os << x.val; }
    friend constexpr istream& operator >> (istream &is, Fp<MOD>& x) noexcept{ return is >> x.val; }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept{
        if (n == 0) return 1; auto t = modpow(a, n/2); t = t*t; if(n & 1) t = t*a; return t; }
};
const int MOD = MODV;
using mint = Fp<MOD>;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(10);
    ll n, m;
    cin >> n >> m;
    vector<ll> dp(n+1, 0);
    vector<bool> a(n, true);
    dp[0] = 1;
    for(ll i=0; i<m; i++){
        ll tmp = 0;
        cin >> tmp;
        a[tmp] = false;
    }
    if(a[1]) dp[1] = 1;

    for(ll i=2; i<=n; i++){
        if(!a[i]) continue;
        if(!a[i-1] && !a[i-2]) dp[i] = 0;
        else{
            if(a[i-1] && a[i-2]) dp[i] = dp[i-1] + dp[i-2];
            else if(!a[i-1]) dp[i] = dp[i-2];
            else dp[i] = dp[i-1];
            dp[i] %= MODV;
        }
    }
    cout << dp[n] << endl;
}

Measured memory_bytes: 1024