#include <cstdio>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cassert>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
#define repeat_from(i,m,n) for (int i = (m); (i) < (n); ++(i))
#define whole(f,x,...) ([&](decltype((x)) y) { return (f)(begin(y), end(y), ## __VA_ARGS__); })(x)
typedef long long ll;
using namespace std;

const ll mod = 1e9+7;

ll powi(ll x, ll y, ll p) {
    assert (y >= 0);
    x = (x % p + p) % p;
    ll z = 1;
    for (ll i = 1; i <= y; i <<= 1) {
        if (y & i) z = z * x % p;
        x = x * x % p;
    }
    return z;
}
ll inv(ll x, ll p) {
    assert ((x % p + p) % p != 0);
    return powi(x, p-2, p);
}
ll choose(ll n, ll r) { // O(n) at first time, otherwise O(1)
    static vector<ll> fact(1,1);
    static vector<ll> ifact(1,1);
    if (fact.size() <= n) {
        int l = fact.size();
        fact.resize( n + 1);
        ifact.resize(n + 1);
        repeat_from (i,l,n+1) {
            fact[i]  = fact[i-1] * i % mod;
            ifact[i] = inv(fact[i], mod);
        }
    }
    r = min(r, n - r);
    return fact[n] * ifact[n-r] % mod * ifact[r] % mod;
}

int main() {
    int m; scanf("%d", &m);
    vector<int> h; for (int t; scanf("%d", &t) != EOF;) h.push_back(t);
    int sum = whole(accumulate, h, 0);
    int blank = m - (sum + h.size()-1);
    if (h.size() == 1 and h[0] == 0) {
        printf("1\n");
    } else if (blank >= 0) {
        int ans = choose(blank + h.size(), h.size());
        printf("%d\n", ans);
    } else {
        printf("NA\n");
    }
    return 0;
}