#include <bits/stdc++.h>
using namespace std;
int dx4[4] = {1, 0, -1, 0};
int dy4[4] = {0, -1, 0, 1};
int dx8[8] = {1, 0, -1, 1, -1, 1, 0, -1};
int dy8[8] = {1, 1, 1, 0, 0, -1, -1, -1};
const int INF = 1e9;
const long long LLINF = 1e18;
const int MAX_V = 1e6 + 1;
const long long mod = 1000000007;
int n, m;
vector<int> v;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n >> m;
  vector<bool> v(n + 1, true);
  for (int i = 0; i < (int)(m); i++) {
    int a;
    cin >> a;
    v[a] = false;
  }
  vector<int> memo(n + 1, 0);
  memo[0] = 1;
  for (int i = (2); i < (int)(n + 1); i++) {
    if (v[i]) {
      if (i == 1)
        memo[i] = memo[i - 1] % mod;
      else
        memo[i] = (memo[i - 1] + memo[i - 2]) % mod;
    } else {
      memo[i] = 0;
    }
  }
  cout << memo[n] << endl;
}
