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