#include <cstdio>
#include <iostream>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <string>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <functional>
#include <queue>
#include <stack>
#include <cmath>
#include <iomanip>
#include <list>
#include <tuple>
#include <bitset>
#include <ciso646>
#include <cassert>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> T;
typedef vector<ll> vec;

inline bool check(ll x, ll y, ll xMax, ll yMax) { return x >= 0 && y >= 0 && xMax > x && yMax > y; }
inline int toint(string s) { int v; istringstream sin(s); sin >> v; return v; }
template<class T> inline string tostring(T x) { ostringstream sout; sout << x; return sout.str(); }
template<class T> inline T sqr(T x) { return x*x; }
template<class T> inline T mypow(T x, ll n) { T res = 1; while (n > 0) { if (n & 1)res = res * x;	x = x * x;	n >>= 1; }return res; }
inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

#define For(i,a,b)	for(ll (i) = (a);i < (b);(i)++)
#define rep(i,n)	For(i,0,n)
#define rFor(i,a,b)	for(ll (i) = (a-1);i >= (b);(i)--)
#define rrep(i,n)	rFor(i,n,0)
#define each(i,n)	for(auto &i : n)
#define clr(a)		memset((a), 0 ,sizeof(a))
#define mclr(a)		memset((a), -1 ,sizeof(a))
#define all(a)		(a).begin(),(a).end()
#define sz(a)		(sizeof(a))
#define tostr(a)	tostring(a)
#define dump(val) 	cerr << #val " = " << val << endl;
#define Fill(a,v)	fill((int*)a,(int*)(a+(sz(a)/sz(*(a)))),v)

const ll dx[8] = { 1, 0, -1, 0, 1, 1, -1, -1 }, dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 };

const ll mod = 1e9 + 7;
const ll INF = 1e17 + 9;

#define int ll
#define double ld

//nCmを n*(n-1)*(n-2)... / (1 * 2 * 3 ... )　の式で求める
//除算を行うために逆元を求める

ll extgcd(ll a, ll b, ll &x, ll &y) {
	ll d = a;
	if (b != 0) {
		d = extgcd(b, a % b, y, x);
		y -= (a / b) * x;
	}
	else {
		x = 1; y = 0;
	}
	return d;
}

ll mod_inverse(ll a, ll m) {
	ll x, y;
	extgcd(a, m, x, y);
	return (m + x % m) % m;
}

const int M = 2000001;
ll fact[M];

ll mod_fact(ll n, ll p, ll &e) {
	e = 0;
	if (n == 0)return 1;
	ll res = mod_fact(n / p, p, e);
	e += n / p;

	if (n / p % 2 != 0)return res * (p - fact[n % p]) % p;
	return res * fact[n % p] % p;
}

ll mod_comb(ll n, ll k, ll p) {
	if (n < 0 || k < 0 || n < k)return 0;
	ll e1, e2, e3;
	ll a1 = mod_fact(n, p, e1), a2 = mod_fact(k, p, e2), a3 = mod_fact(n - k, p, e3);
	if (e1 > e2 + e3) return 0;
	return a1 * mod_inverse(a2 * a3 % p, p) % p;
}

signed main() {
	fact[0] = 0;
	fact[1] = 1;
	for (int i = 2; i < M; i++) {
		fact[i] = (fact[i - 1] * i) % mod;
	}
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	int m;
	cin >> m;
	string s;
	getline(cin, s);
	getline(cin, s);
	stringstream ss(s);

	int sum = -1, cnt = 1;
	int t;
	while (ss >> t) {
		if (t == 0) {
			cout << 1 << endl;
			return 0;
		}
		sum += t + 1;
		cnt++;
	}
	int res = m - sum;
	if (res < 0) {
		cout << "NA" << endl;
		return 0;
	}
	cout << mod_comb(cnt + res - 1, res, mod) << endl;
	return 0;
}