#include <bits/stdc++.h>
using namespace std;
int n, m;
vector<int> a(1000010, 0);
int ans = 0;
void dfs(int k) {
  if (a.at(k) == 1) return;
  if (k == n) {
    if (ans == 1000000007) ans = 0;
    ans++;
  }
  if (k > n) return;
  dfs(k + 1);
  dfs(k + 2);
}
int main() {
  cin >> n >> m;
  for (int64_t i = (0); i < (m); i++) {
    int x;
    cin >> x;
    a.at(x) = 1;
  }
  dfs(0);
  cout << ans << endl;
}
