#include <bits/stdc++.h>
using namespace std;
int main(){
  int n,m;
  cin >> n >> m;
  if(m==0){
    vector<int> a(1);
  }else{
    vector<int> a(m);
  }
  int i;
  for(i=0;i<m;i++){
    cin >> a[i];
  }

  long ans;
  vector<long> b(n+1);
  b[0] = 1;
  if(a[0] == 1){
    b[1] = 0;
  }else{b[1] = 1;}
    int j =0;
  while(j != m && a[j] == 1)j++;
  for(i=2;i<n+1;i++){
    while(j != m && a[j] == a[j+1])j++;
    if(i ==a[j]){
      b[i] = 0;
      if(j!=m)
        j++;
    }else{
      b[i] = b[i-1] + b[i-2];
    }
    if(b[i] > 1000000007)b[i] %= 1000000007;
  }
  cout << b[n] << endl;
}