#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
int main() {
  int N, M;
  cin >> N >> M;
  vector<int> oks(N + 1, true);
  for (int i = 0; i < M; ++i) {
    int a;
    cin >> a;
    oks[a] = false;
  }
  vector<long long int> dp(N + 1);
  dp[0] = 1;
  for (int now = 0; now < N; ++now) {
    for (int next = now + 1; next <= min(N, now + 2); ++next) {
      if (oks[next]) {
        dp[next] += dp[now];
        dp[next] %= mod;
      }
    }
    cout << dp[N] << endl;
    return 0;
  }
}
