#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, a;
  cin >> n >> m >> a;
  long long dp[10010] = {0};
  dp[0] = 1;
  if (a == 1)
    cin >> a;
  else
    dp[1] = 1;
  for (long long i = (2); i < (n + 1); i++) {
    if (i == a) {
      cin >> a;
    } else {
      dp[i] += dp[i - 1] + dp[i - 2];
      dp[i] %= 1000000007;
    }
  }
  cout << dp[n] << endl;
}
