#include <bits/stdc++.h>
using namespace std;

using pii = pair<int,int>;
using ll = long long;
#define rep(i, j) for(int i=0; i < (int)(j); i++)
#define all(v) v.begin(),v.end()

class ModInt{
  public:
    static const ll MOD = 1000000007LL; 
    ll x;
    ModInt():x(0){};
    ModInt(ll x){
        while(x < 0) x += MOD;
        x %= MOD;
        this->x = x;
    }
    ModInt& operator += (const ModInt &l){ x += l.x; if( x >= MOD) x -= MOD; return *this; }
    ModInt& operator -= (const ModInt &l){ x -= l.x; if( x < 0 ) x += MOD; return *this; }
    ModInt& operator *= (const ModInt &l){ x = (x * l.x) % MOD; return *this; }
    ModInt operator +(const ModInt &l) const { return ModInt( x + l.x); }
    ModInt operator -(const ModInt &l) const { return ModInt( x - l.x); }
    ModInt operator *(const ModInt &l) const { return ModInt( x * l.x); }
};

// @warning rの部分はmodとってはいけない
ModInt pow(const ModInt &n, ll r){
    if(r == 0) return ModInt(1);
    ModInt ret = pow(n, r / 2);
    ret *= ret;
    if(r % 2 != 0) ret = ret * n;
    return ret;
}

// @waring nはMODと互いに素
ModInt inverse(const ModInt &n){
    return pow(n, ModInt::MOD - 2);
}

ModInt factorial(ll n){
    ModInt ret(1);
    do {
        ret *= n;
    } while(--n > 0);
    return ret;
}

ostream& operator << (std::ostream& os,const ModInt& a){ os << a.x; return os;}
istream& operator >> (std::istream& is,ModInt& a){ is >> a.x; return is;}


class Solver {
  public:
    bool solve() {
        int M; cin >> M;
        vector<int> H; {
            int a;
            while(cin >> a) H.push_back(a);
        }

        int N = H.size();
        int left = M - accumulate(all(H), 0) - (N - 1);
        if(left < 0) cout << "NA" << endl;
        else if((N == 1 and H[0] == 0) or left == 0) cout << 1 << endl;        
        else cout << factorial(N + left) * inverse(factorial(left) * factorial(N)) << endl;        
        return 0;
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    Solver s;
    s.solve();
    return 0;
}