#include <bits/stdc++.h>
long long kai(long long n, long long j) {
  long long k;
  if (j == 0) {
    k = 1;
  } else {
    k = n + 1;
  }
  return k;
}
int main() {
  long long a, b = 0, n, m, o = 0, p = 1, s, t, u, h;
  scanf("%lld %lld", &n, &m);
  for (int i = 0; i < m; i++) {
    scanf("%lld", &a);
    if (a == b) {
      printf("0\n");
      exit(0);
    }
    a = a - 1;
    s = (a - b) / 2;
    t = (a - b) % 2;
    h = kai(s, t);
    o += h;
    for (long long i = 1; i <= s; i++) {
      h = h * (s + t + i) * (s + 1 - i) / (t + 2 * i) / (t + 2 * i - 1);
      o += h;
      if (o > 1000000007) {
        o -= 1000000007;
      }
    }
    p *= o;
    if (p >= 1000000007) {
      p %= 1000000007;
    }
    o = 0;
    b = a + 2;
  }
  s = (n - b) / 2;
  t = (n - b) % 2;
  h = kai(s, t);
  o += h;
  for (long long i = 1; i <= s; i++) {
    h = h * (s + t + i) * (s + 1 - i) / (t + 2 * i) / (t + 2 * i - 1);
    o += h;
    if (o > 1000000007) {
      o -= 1000000007;
    }
  }
  p *= o;
  p = p % 1000000007;
  printf("%lld\n", p);
  return 0;
}
