#include <bits/stdc++.h>
using namespace std;

#define int long long
#define MOD 1000000007

int f(int n){
    if(n == 0) return 1;
    return n * f(n-1) % MOD;
}

signed main(){
    int n, k;
    cin >> n >> k;
    int a[100];

    for(int i = 0;i < k;i++){
        cin >> a[i];
    }
    sort(a, a+k);
    
    int old = 0;
    for(int i = 0;i < k;i++){
        if(a[i] != 0) n--;

        if((~a[i]) & old){
            cout << 0 << endl;
            return 0;
        }

        old = a[i];

    }


    cout << f(n) << endl;
    
    return 0;
}