#include <bits/stdc++.h>
using namespace std;
#define int long long   // <-----!!!!!!!!!!!!!!!!!!!

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> Pii;
typedef tuple<int, int, int> TUPLE;
typedef vector<int> V;
typedef vector<V> VV;
typedef vector<VV> VVV;
typedef vector<vector<int>> Graph;
const int inf = 1e9;
const int mod = 1e9 + 7;

ll powmod (ll a, ll p) {
	ll ans = 1ll;
	ll mul = a;
	for (; p > 0ll; p >>= 1ll, mul = (mul * mul) % mod) {
		if ((p & 1ll) == 1ll) ans = (ans * mul) % mod;
	}
	return ans;
}

ll getRev(ll x) {
	return powmod(x, mod - 2ll);
}

int C(int n, int k) {
    int ret = 1ll;
    for (int i = n; i > n - k; i--) {
        (ret *= i) %= mod;
    }
    for (int i = k; i >= 1ll; i--) {
        (ret *= getRev(i)) %= mod;
    }
    return ret;
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int M;
    cin >> M;
    V h;
    string s;
    cin.ignore();
    getline(cin, s);
    stringstream ss(s);
    int x;
    while (ss >> x) h.emplace_back(x);
    int K = h.size();

    int sm = accumulate(all(h), 0ll);
    if (sm == 0ll) {
        cout << 0ll << endl;
        return 0;
    }
    if (M - sm + 1ll < K) {
        cout << "NA" << endl;
        return 0;
    }
    cout << C(M - sm + 1ll, K) << endl;
}