#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int ll
#define rep(i,n) for(int i = 0; i < (int)(n); ++i)
#define all(c) begin(c), end(c)
//#define fill(c,v) fill(decltype(v)*(begin(c)), decltype(v)*(end(c)), v)

const ll mod = 1000000007;

ll modpow(ll x, ll y, ll m){
    if(y==0) return 1;
    ll res = modpow(x,y/2,m);
    return res * res % m * (y&1 ? x : 1) % m;
}

ll modinv(ll x, ll m){
    return modpow(x, m-2, m);
}

decltype(0) main(){
    int W;
    cin >> W;
    int x;
    int k = 0;
    int zero = 0;
    while(cin >> x){
        W -= x;
        ++k;
        zero |= x == 0;
    }
    if(W+1 < k){
        cout << "NA" << endl;
    } else if(k == 1 && zero){
        cout << 1 << endl;
    } else {
        ll num = 1;
        ll den = 1;
        rep(i,k){
            num *= W+1-i;
            den *= i+1;
            num %= mod;
            den %= mod;
        }
        num *= modinv(den, mod);
        num %= mod;
        cout << num << endl;
    }
}