#include <bits/stdc++.h>
using namespace std;
long long n, m, x, a[100010] = {1};
int main() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    cin >> x;
    a[x] = -1;
  }
  for (int i = 1; i <= n; i++) {
    if (a[i] != -1) {
      if (a[i - 1] != -1) a[i] = (a[i] + a[i - 1]) % 1000000007;
      if (a[i - 2] != -1) a[i] = (a[i] + a[i - 1]) % 1000000007;
    }
  }
  if (a[n] == -1)
    cout << 0;
  else
    cout << a[n];
  return 0;
}
