#include <bits/stdc++.h>
using namespace std;
long long fivo(int n) {
  if (n == 1 || n == 2)
    return 1;
  else
    return fivo(n - 1) + fivo(n - 2);
}
int main() {
  int n, m;
  cin >> n >> m;
  if (m != 0) {
    vector<long long> a(m);
    for (int i = 0; i < m; i++) cin >> a[i];
    vector<long long> sa(m + 1);
    long long ans = 1;
    bool flag = true;
    for (int i = 0; i < m - 1; i++) {
      if (a[i + 1] - a[i] == 1) {
        flag = false;
        break;
      }
    }
    if (!flag)
      cout << 0;
    else {
      sa[0] = a[0];
      sa[m] = n - a[m - 1];
      for (int i = 1; i < m; i++) sa[i] = a[i] - a[i - 1] - 1;
      for (int i = 0; i < m + 1; i++) {
        ans *= fivo(sa[i]);
      }
      cout << ans % 1000000007;
    }
  } else {
    cout << fivo(n + 1) % 1000000007;
  }
}
