#include <bits/stdc++.h>
using namespace std;
constexpr long long int mod = 1000000000 + 7;
int main() {
  int n, m;
  cin >> n >> m;
  vector<long long> v(n + 1, 0), w(m);
  for (int i = 0; i < m; i++) {
    cin >> w[i];
  }
  v[0] = 1;
  int k = 0;
  if (w[0] == 1) {
    k = min(k + 1, m - 1);
  } else {
    v[1] = v[0];
  }
  for (int i = 2; i <= n; i++) {
    if (w[k] == i) {
      k = min(k + 1, m - 1);
    } else {
      v[i] += v[i - 1] + v[i - 2];
      v[i] %= mod;
    }
  }
  cout << v[n] << endl;
}
