#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long long fac[1000020], finv[1000020], inv[1000020];
long long mod = 1000000007;
void COMinit() {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for (int i = 2; i < 1000020; i++) {
		fac[i] = fac[i - 1] * i % mod;
		inv[i] = mod - inv[mod % i] * (mod / i) % mod;
		finv[i] = finv[i - 1] * inv[i] % mod;
	}
}
long long COM(long long n, long long k) {
	if (n < k) return 0;
	if (n < 0 || k < 0) return 0;
	return fac[n] * (finv[k] * finv[n - k] % mod) % mod;
}
int main() {
	long long m;
	cin >> m;
	long long co = 0;
	long long n = 0;
	string s;
	getline(cin, s);
	getline(cin, s);
	string h1 = "";
	for (int i = 0; i < s.size(); i++) {
		if (s[i] == ' ') {
			long long h = stoll(h1);
			n += h;
			co++;
			h1 = "";
		}
		else {
			h1 += s[i];
		}
	}
	long long h = stoll(h1);
	n += h;
	co++;
	h1 = "";
	if (m - n < co - 1) {
		cout << "NA" << endl;
	}
	else if (n == 0) {
		cout << "1" << endl;
	}
	else {
		COMinit();
		cout << COM(m - n + 1, co) << endl;
	}
}