#include <bits/stdc++.h>
using namespace std;
const int MAX = 510000;
const int MOD = 1000000007;
long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}
long long ncr(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main(void) {
  COMinit();
  int64_t N, M;
  int64_t a, last;
  int64_t move, skip;
  int64_t sum, tempsum;
  cin >> N >> M;
  last = 0;
  sum = 1;
  for (int i = 0; i < M; i++) {
    cin >> a;
    move = a - 1 - last;
    skip = move / 2;
    tempsum = 0;
    for (int j = 0; j <= skip; j++) {
      tempsum += ncr(move - j, j);
    }
    sum = (sum * tempsum) % MOD;
    last = a + 1;
  }
  move = N - last;
  skip = move / 2;
  tempsum = 0;
  for (int j = 0; j <= skip; j++) {
    tempsum += ncr(move - j, j);
  }
  sum = (sum * tempsum) % MOD;
  cout << sum % MOD << endl;
  return 0;
}
