#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  cin >> N >> M;
  vector<long long> a(N + 1, 0);
  vector<int> noentry(M);
  for (int i = 0; i < M; i++) {
    cin >> noentry[i];
  }
  a[0] = 1;
  if (M != 0) {
    a[noentry[0]] = -1;
    for (int i = 1; i < noentry.size(); i++) {
      if (noentry[i] - 1 == noentry[i - 1]) {
        cout << 0 << endl;
        return 0;
      }
      a[noentry[i]] = -1;
    }
  }
  if (a[1] == 0) {
    a[1] = 1;
  }
  for (int i = 2; i < a.size(); i++) {
    if (a[i] == -1) continue;
    if (a[i - 1] == -1) {
      a[i] = a[i - 2];
      continue;
    }
    if (a[i - 2] == -1) {
      a[i] = a[i - 1];
      continue;
    }
    a[i] = a[i - 1] + a[i - 2];
  }
  cout << a[N] % 1000000007 << endl;
  return 0;
}
