# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <tuple>
# include <unordered_map>
# include <numeric>
# include <complex>
# include <bitset>
# include <random>
# include <chrono>
# include <cstdlib>
# include <tuple>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
constexpr int INF = 2147483647;
constexpr int HINF = INF / 2;
constexpr double DINF = 100000000000000000.0;
constexpr double HDINF = 50000000000000000.0;
constexpr long long LINF = 9223372036854775807;
constexpr long long HLINF = 4500000000000000000;
const double PI = acos(-1);
int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); };
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); };
# define ALL(x)      (x).begin(),(x).end()
# define UNIQ(c)     (c).erase(unique(ALL((c))),(c).end())
# define LOWER(s)    transform(ALL((s)),(s).begin(),TL<char>)
# define UPPER(s)    transform(ALL((s)),(s).begin(),TU<char>)
# define FOR(i,a,b)  for(LL i=(a);i<(b);i++)
# define RFOR(i,a,b) for(LL i=(a);i>=(b);i--)
# define REP(i,n)    FOR(i,0,n)
# define INIT        std::ios::sync_with_stdio(false);std::cin.tie(0)

LL MOD = 1000000007;
LL combi(LL N_, LL C_) {
	const int NUM_ = 1010101;
	static LL fact[NUM_ + 1], factr[NUM_ + 1], inv[NUM_ + 1];
	if (fact[0] == 0) {
		inv[1] = fact[0] = factr[0] = 1;
		for (int i = 2; i <= NUM_; ++i) inv[i] = inv[MOD % i] * (MOD - MOD / i) % MOD;
		for (int i = 1; i <= NUM_; ++i) fact[i] = fact[i - 1] * i%MOD, factr[i] = factr[i - 1] * inv[i] % MOD;
	}
	if (C_<0 || C_>N_) return 0;
	return factr[C_] * fact[N_] % MOD*factr[N_ - C_] % MOD;
}
LL hcomb(int P_, int Q_) { return (P_ == 0 && Q_ == 0) ? 1 : combi(P_ + Q_ - 1, Q_); }

LL modpow(LL a, LL n = MOD - 2) {
	LL r = 1;
	while (n) r = r*((n % 2) ? a : 1) % MOD, a = a*a%MOD, n >>= 1;
	return r;
}
 
vector<int>h;
int sum = 0;
int main() {
	int m;
	cin >> m;
	int n;
	while (cin >> n) {
		h.emplace_back(n);
		sum += n;
	}
	if (sum + h.size()-1> m) {
		cout << "NA" << endl;
		return 0;
	}
	if (sum == 0) {
		cout << 1 << endl;
		return 0;
	}
	int num = m - (sum + h.size() - 1);
	cout << (combi(num + h.size(), h.size())) << endl;
}