#include <iostream>
using namespace std;

const int MAXN = 1e6 + 10, MOD = 1e9 + 7;
long long dp[MAXN];
bool O[MAXN];

int main() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int a;
    cin >> a;
   O[a] = 1; 
  }
  dp[0] = 1;
  for (int i = 1; i <= n; i++) {
   if (O[i])
     continue;
   dp[i] = dp[i - 1] + dp[i - 2];
    dp[i] %= MOD;
  }
  cout << dp[n];
}