#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)


typedef long long ll;
ll mo = 1000000007;
const int NUM_FAC = 2000001;
ll modfact(ll x) {
	static ll _fact[NUM_FAC + 1];
	if (_fact[0] == 0) {
		_fact[0] = 1;
		for (int i = 1; i <= NUM_FAC; ++i) _fact[i] = _fact[i - 1] * i%mo;
	}
	return _fact[x];
}
ll modpow(ll a, ll n) {
	ll r = 1;
	while (n) r = r*((n % 2) ? a : 1) % mo, a = a*a%mo, n >>= 1;
	return r;
}
ll moddiv(ll a, ll b)
{
	ll ap_2 = modpow(b, mo - 2);
	return (a * ap_2) % mo;
}
ll aCb(ll a, ll b) {
	return moddiv(modfact(a), (modfact(a-b) * modfact(b))%mo);
}
ll nHk(ll n, ll k)
{
	return aCb(n + k - 1, k - 1);
}
//-----------------------------------------------------------------
int M;
vector<int> H;
//-----------------------------------------------------------------
int main() {
	cin >> M;

	int x;
	while (cin >> x) H.push_back(x);

	if (H.size() == 1 && H[0] == 0) {
		printf("1\n");
		return 0;
	}

	int sum = 0;
	rep(i, 0, H.size()) sum += H[i];
	int a = M - sum - (H.size() - 1);
	int b = H.size() + 1;

	if (a < 0) {
		cout << "NA" << endl;
		return 0;
	}

	ll ans = nHk(a, b);
	cout << ans << endl;
}