#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const int MOD = 1000000007;
template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) {
  return s << "(" << p.first << ", " << p.second << ")";
}
template <typename T>
ostream &operator<<(ostream &s, const vector<T> &v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i];
    if (i < len - 1) s << "	";
  }
  return s;
}
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  long long n, m;
  cin >> n >> m;
  vector<long long> way(n + 1, 0);
  vector<long long> brk(m + 1, 0);
  for (long long i = (0); i < (m); i++) {
    long long tmp;
    cin >> tmp;
    brk[tmp] = 1;
  }
  long long ans = 0;
  way[0] = 1;
  if (brk[1] == 1) {
    way[1] = 0;
  } else {
    way[1] = 1;
  }
  for (long long i = (2); i < (n + 1); i++) {
    if (brk[i] == 1) {
      way[i] = 0;
    } else {
      way[i] = way[i - 1] + way[i - 2];
      way[i] %= MOD;
    }
  }
  ans = way[n];
  cout << ans << endl;
  return 0;
}
