#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int mod = 1000000007;
struct mint {
  ll x;
  mint(ll x = 0) : x(x % mod) {}
  mint operator-() const { return mint(-x); }
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) {
      x -= mod;
    }
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod - a.x) >= mod) {
      x -= mod;
    }
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) % mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t) {
      return 1;
    }
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) {
      a *= *this;
    }
    return a;
  }
  mint inv() const { return pow(mod - 2); }
  mint& operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) { return mint(*this) /= a; }
};
istream& operator>>(istream& is, mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
int main() {
  int n, m;
  cin >> n >> m;
  vector<bool> as(m, false);
  for (int i = 0; i < (int)(m); i++) {
    int a;
    cin >> a;
    as[a] = true;
  };
  vector<mint> dp(n + 2, 0);
  dp[0] = 1;
  for (int i = 0; i < (int)(n); i++) {
    if (!as[i + 1]) {
      dp[i + 1] += dp[i];
    }
    if (!as[i + 2]) {
      dp[i + 2] += dp[i];
    }
  }
  cout << dp[n] << endl;
  return 0;
}
