#include <bits/stdc++.h>
using namespace std;

int main(){

  int N,M;
  cin >> N >> M;
  vector<int> broken(N+1);

  for(int i = 0;i < M;i++){
    int a;
    cin >> a;
    broken[a] = 1;
  }
  vector<int> dp(n+2);//dp[n+1]は0で初期化.
  const int mod = 1000000007;
  dp[n] = 1;
  for(int i = n - 1;i >= 0;i--){
    if(broken[i]){
      dp[i] = 0;
      continue;
    }
    dp[i] = (dp[i + 1] + dp[i + 2]) % mod;


  }

  cout << dp[0] << endl;

  return 0;


}
