/* -*- coding: utf-8 -*-
 *
 * 389.cc: No.389 ロジックパズルの組み合わせ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 1000000;

typedef long long ll;
const ll MOD = 1000000007;

/* typedef */

/* global variables */

ll fracs[MAX_M + 1];

/* subroutines */

ll powmod(ll a, int n) {  // a^n % MOD
  ll pm = 1;
  while (n > 0) {
    if (n & 1) pm = (pm * a) % MOD;
    a = (a * a) % MOD;
    n >>= 1;
  }
  return pm;
}

/* main */

int main() {
  int m;
  cin >> m;

  int k = 0, sum = 0;
  for (;;) {
    int ai;
    cin >> ai;
    if (cin.eof()) break;
    sum += ai;
    k++;
  }
  //printf("k=%d, sum=%d\n", k, sum);

  if (sum == 0) {
    puts("1");
    return 0;
  }

  int n = m - sum + 1;
  if (n < k) {
    puts("NA");
    return 0;
  }

  fracs[0] = 1;
  for (int i = 1; i <= n; i++) fracs[i] = (fracs[i - 1] * i) % MOD;

  ll ans =
    fracs[n] * powmod(fracs[n - k], MOD - 2) % MOD *
    powmod(fracs[k], MOD - 2) % MOD;
  printf("%lld\n", ans);
  return 0;
}