#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 10;
const int mod = 1e9 + 7;
int n, m, a[N], k;
typedef long long ll;
ll f[N], g[N];
ll ans = 1;
ll qPow(ll x, ll k) {
    ll res = 1;
    while (k > 0) {
        if (k & 1) {
            res = res * x % mod;
        }
        x = x * x % mod;
        k >>= 1;
    }
    return res;
}
void init() {
    f[0] = g[0] = 1;
    for (int i = 1; i < N; i++) {
        f[i] = f[i - 1] * i % mod;
        g[i] = qPow(i, mod - 2) * g[i - 1] % mod;
    }
}
int main() {
    init();
    scanf("%d%d", &n, &m);
    k = n / m;
    for (int i = 1; i <= m; i++) {
        scanf("%d", &a[i]);
    }
    sort(a + 1, a + m + 1);
    for (int i = m; i >= 1; i--) {
        ll c = n - a[i] - k * (m - i);
        ans = ans * f[c] % mod * g[k - 1] % mod * g[c - k + 1] % mod;
    }
    printf("%lld\n", ans);
    return 0;
}