#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 i = 2; i < N + 1; i++) {
    if (oks[i]) {
      dp[i] = dp[i - 1] + dp[i - 2];
      dp[i] %= mod;
    }
    dp[i] = dp[i] % mod;
  }
  cout << dp[N] << endl;
  return 0;
}
