#include <bits/stdc++.h>
using namespace std;
using INT = long long;
using UINT = unsigned long long;
unsigned gcd(unsigned a, unsigned b) {
  while (1) {
    if (a < b) swap(a, b);
    if (!b) break;
    a %= b;
  }
  return a;
}
INT dp[10010];
bool br[10010] = {false};
int main() {
  int n, m;
  cin >> n >> m;
  for (size_t i = 0; i < m; i++) {
    int a;
    cin >> a;
    br[a] = true;
  }
  dp[0] = 1;
  dp[1] = 1;
  for (size_t i = 2; i <= n; i++) {
    dp[i] = (!br[i - 2] ? dp[i - 2] : 0) + (!br[i - 1] ? dp[i - 1] : 0);
    dp[i] %= 1000000007;
  }
  cout << dp[n] << endl;
  return 0;
}
