#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<N;i++) {
    int a;
    cin >> a;
    broken[a]=1;
  }
  vector<int> dp(n+2);
  dp[n]=1;
  const int mod=1000000007;
  for(int i=n-1;i>=0;i--){
    if(braken[i]){
      dp[i]=0;
      continue;
    }
    dp[i]=(dp[i+1]+dp[i+2])% mod;
  }
  cout << dp[0] << endl;
}
