#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  cin >> N >> M;
  unordered_set<int> A;
  for (int i = 0; i < M; ++i) {
    int a;
    cin >> a;
    A.insert(a);
  }
  vector<int> dp(N + 1, 0);
  dp[0] = 1;
  for (int i = 1; i <= N; ++i) {
    if (find(A.begin(), A.end(), i) != A.end()) {
      continue;
    }
    if (find(A.begin(), A.end(), i - 1) == A.end()) {
      dp[i] = dp[i - 1];
    }
    if (find(A.begin(), A.end(), i - 2) == A.end()) {
      if (i - 2 >= 0) dp[i] = (dp[i] + dp[i - 2]) % 1000000007;
    }
  }
  cout << dp[N] << endl;
  return 0;
}
