#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  int dp[n + 1], j = 0;
  vector<int> treads(m);
  for (int i = 0; i < m; i++) {
    cin >> treads[i];
  }
  dp[0] = 1;
  for (int i = 1; i <= n; i++) {
    if (i == treads[j]) {
      dp[i] = 0;
      j++;
      continue;
    } else {
      if (i == 1)
        dp[i] = dp[0];
      else
        dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007;
    }
  }
  cout << dp[n] << "\n";
}
