#include <bits/stdc++.h>
using namespace std;
#define FILE(x) freopen(x".in", "r", stdin);freopen(x".out", "w", stdout);
const int mod = 1e9 + 7;
int n, m, a[1000001];
long long fact[1000001], cnt, ans = 1;
void init(){
	fact[0] = 1;
	for (int i = 1; i <= 1e6; i++){
		fact[i] = fact[i - 1] * i % mod;
	}
	return;
}
long long qpow(long long a, long long b){
	long long res = 1;
	while (b){
		if (b & 1){
			res *= a;
			res %= mod;
		}
		a *= a;
		a %= mod;
		b = b >> 1;
	}
	return res;
}
long long C(long long n, long long m){
	return fact[n] * qpow(fact[n - m] * fact[m] % mod, mod - 2) % mod;
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	init();
	cin >> n >> m;
	for (int i = 1; i <= m; i++){
		cin >> a[i];
	}
	if (a[1] != 1){
		cout << "0";
		return 0;
	}
	cnt = n - a[m];
	for (int i = m; i >= 1; i--){
		ans *= C(cnt, n / m - 1);
		ans %= mod;
		cnt -= n / m - 1;
		cnt += a[i] - a[i - 1] - 1;
	}
	cout << ans;
	return 0;
}