#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstring>
#include <vector>
#include <set>

using namespace std;

typedef long long ll;
typedef double db;

#define forab(i, a, b) for(int i = int(a); i < int(b); ++i)
#define forba(i, b, a) for(int i = int(b) - 1; i >= int(a); --i)
#define forn(i, n) forab(i, 0, n)
#define pb push_back

const ll P = (ll)1e9 + 7;

ll n;
int k;

ll pow(ll a, ll b) {
    if (b == 0)
        return 1;
    if (b % 2 == 0)
        return pow((a * a) % P, b / 2);
    return (pow(a, b - 1) * a) % P;
}

int main()
{
    //freopen("01", "r", stdin);
    while (true) {
        cin >> n >> k;
        if (n == 0 && k == 0)
            break;
        ll col = 0, tmp;
        forn(i, k) {
            cin >> tmp;
            if (tmp != 1 && tmp / 2 <= n)
                col += min(n, tmp - 1) - (tmp / 2);
        }
        ll ans = pow(2ll, n - col);
        cout << ans % P << '\n';
    }
    return 0;
}