#include <bits/stdc++.h>
using namespace std;
template <class X>
void pr(X test) {
  cout << test << endl;
}
template <class X>
void prr(X test) {
  for (auto it : test) {
    cout << it << endl;
  }
}
template <class X>
void prrr(X test) {
  int f = 0;
  for (auto it : test) {
    cout << (f++ != 0 ? " " : "") << it;
  }
  cout << endl;
}
template <typename X>
istream &operator>>(istream &i, vector<X> &v) {
  for (X &x : v) i >> x;
  return i;
}
class UF {
 public:
  int *id;
  int cnt;
  int *sz;
  UF(int N) {
    cnt = N;
    id = new int[N];
    sz = new int[N];
    for (int i = 0; i < N; i++) {
      id[i] = i;
      sz[i] = 1;
    }
  }
  ~UF() {
    delete[] id;
    delete[] sz;
  }
  int find(int p) {
    int root = p;
    while (root != id[root]) root = id[root];
    while (p != root) {
      int newp = id[p];
      id[p] = root;
      p = newp;
    }
    return root;
  }
  void merge(int x, int y) {
    int i = find(x);
    int j = find(y);
    if (i == j) return;
    if (sz[i] < sz[j]) {
      id[i] = j;
      sz[j] += sz[i];
    } else {
      id[j] = i;
      sz[i] += sz[j];
    }
    cnt--;
  }
  bool connected(int x, int y) { return find(x) == find(y); }
  int count() { return cnt; }
};
vector<long long> divv(long long n) {
  vector<long long> v;
  for (long long i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      v.push_back(i);
      if (i * i != n) v.push_back(n / i);
    }
  }
  sort(v.begin(), v.end());
  return v;
}
bool chk(string &s, long long a, long long b) {
  for (long long i = a - 1; i < b - 1; i++) {
    auto j = i + 1;
    if (s[i] == '#' && s[j] == '#') {
      return false;
    }
  }
  return true;
}
long long fun(long long u) {
  long long i, a, b, c;
  for (i = 0, b = 1, c = 0; i < u; i++) {
    a = b;
    b = c;
    c = a + b;
  }
  return c;
}
int main() {
  long long n, x, m;
  cin >> n >> m;
  vector<long long> v(m), kai(n, 0);
  cin >> v;
  for (long long i = 0; i < m; i++) {
    kai[v[i] - 1] = 1;
  }
  bool b = true;
  long long len = 1;
  vector<long long> vs;
  for (long long i = 0; i < n; i++) {
    if (kai[i] != 0) {
      if (!b) {
        pr(0);
        return 0;
      }
      b = false;
      if (len > 0) vs.push_back(len);
      len = 0;
    } else {
      b = true;
      len++;
    }
  }
  if (b) vs.push_back(len);
  long long sum = 1;
  for (long long i = 0; i < vs.size(); i++) {
    sum *= (fun(vs[i]) % 1000000007);
    sum %= 1000000007;
  }
  pr(sum);
  return 0;
}
