#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  cin >> N >> M;
  vector<long long int> s(M), t(N), d(M + 1);
  for (int i = 0; i < M; ++i) {
    cin >> s[i];
  }
  t[0] = 1;
  t[1] = 1;
  d[0] = s[0] - 1;
  if (M == 0) {
    for (int i = 2; i < N; ++i) {
      t[i] = t[i - 1] + t[i - 2];
      t[i] = t[i] % 1000000007;
    }
    cout << t[N - 1] % 1000000007 << endl;
  } else {
    if (M >= 2) {
      for (int i = 1; i < M; ++i) {
        d[i] = s[i] - s[i - 1];
      }
    }
    d[M] = N - s[M - 1];
    int max_d = *max_element(d.begin(), d.end());
    int min_d = *min_element(d.begin(), d.end());
    if (min_d <= 1 && d[0] != 1 && d[0] != 0) {
      cout << 0 << endl;
    } else {
      for (int i = 2; i < max_d; ++i) {
        t[i] = t[i - 1] + t[i - 2];
        t[i] = t[i] % 1000000007;
      }
      long long int sum = 1;
      for (int i = 1; i < M; ++i) {
        sum = sum * t[d[i] - 2];
        sum = sum % 1000000007;
      }
      sum = sum * t[d[0]] * t[d[M] - 1];
      cout << sum % 1000000007 << endl;
    }
  }
}
