#include <iostream>
#define int long long
using namespace std;

int m, k, sigma;
const int mod = 1000000007;

void input() {
	int t;
	
	cin >> m;
	k = 0; sigma = 0;
	while (cin >> t) {
		k++;
		sigma += t;
	}
}

int power(int a, int n) {
	if (n == 0) return 1;
	if (n % 2 == 0) return power((a * a) % mod, n / 2) % mod;
	return (a * power(a, n - 1)) % mod;
}

int fact(int n) {
	int ret = 1;
	for (int i = 1; i <= n; i++) { ret *= i; ret %= mod; }
	return ret;
}

int comb(int n, int k) {
	int a = fact(n);
	int b = power(fact(n - k), mod - 2);
	int c = power(fact(k), mod - 2);
	a *= b; a %= mod;
	a *= c; a %= mod;
	return a;
}

signed main() {
	input();
	int s = m - sigma - k + 1;
	if (s < 0) { cout << "NA" << endl; return 0; }
	if (sigma == 0) { cout << 1 << endl; return 0; }
	cout << comb(s + k, k) << endl;
	return 0;
}