#include <bits/stdc++.h>
using namespace std;
int n;
const long long mod = 1e9 + 7;
long long a[100005] = {1, 1, 2, 3, 5};
bool vis[100005];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  while (m--) {
    int ab;
    scanf("%d", &ab);
    a[ab] = 0;
    vis[ab] = 1;
  }
  for (int i = 2; i <= n; i++) {
    if (vis[i] == 1) continue;
    a[i] = a[i - 1] + a[i - 2];
    a[i] %= mod;
  }
  printf("%lld", a[n] % mod);
  return 0;
}
