#include <bits/stdc++.h>
using namespace std;
int main() {
  int mod = 1e9 + 7;
  int N, M;
  cin >> N >> M;
  vector<int> aa(M);
  for (int k = 0; k < M; k++) {
    cin >> aa[k];
  }
  vector<int> ans(N + 1);
  ans[0] = 1;
  for (int k = 0, l = 0; k <= N; k++) {
    if (aa[l] == k) {
      l++;
      continue;
    }
    if (k > 0) {
      ans[k] += ans[k - 1];
    }
    if (k > 1) {
      ans[k] += ans[k - 2];
    }
    ans[k] %= mod;
  }
  cout << ans[N] << endl;
}
