#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  cin >> N;
  cin >> M;
  int a[M];
  int ai[N];
  for (int i = 0; i < N; ++i) {
    ai[i] = 1;
  }
  for (int i = 0; i < M; ++i) {
    cin >> a[i];
    ai[a[i]] = 0;
  }
  int dp[N];
  dp[0] = 1;
  if (ai[1] == 0)
    dp[1] = 0;
  else
    dp[1] = 1;
  for (int i = 2; i < N; ++i) {
    dp[i] = (dp[i - 1] * ai[i - 1] + dp[i - 2] * ai[i - 2]) % 1000000007;
  }
  cout << dp[N - 1];
}
