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