#include <bits/stdc++.h>
const long long INF = 1001001001001001001;
const long long MOD = (long long)1e9 + 7;
const double EPS = 1e-9;
using namespace std;
using Pii = pair<long long, long long>;
using vii = vector<long long>;
template <class T>
using PS_queue = priority_queue<T, vector<T>, greater<T> >;
template <class T>
using vv = vector<T>;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  fill((T *)array, (T *)(array + N), val);
}
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
struct edge {
  long long from, to, cost;
};
long long dy[] = {0, 1, -1, 0};
long long dx[] = {1, 0, 0, -1};
long long n, m, dp[100005];
vii a;
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n >> m;
  a.resize(m);
  for (long long i = 0; i < m; i++) {
    long long t;
    cin >> t;
    a[t] = 1;
  }
  dp[n] = 1;
  for (long long i = n - 1; i >= 0; i--) {
    if (a[i]) {
      dp[i] = 0;
      continue;
    }
    dp[i] = (dp[i + 1] + dp[i + 2]) % MOD;
  }
  cout << dp[0] << endl;
  return 0;
}
