#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <math.h>
#include <cassert>
#include <bitset>
#include <map>
#include <algorithm>
#include <iterator>
#include <string>
#include <utility>
#include <numeric>
#include <regex>
#include <complex>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>
ostream &operator<<(ostream &os,const pair<T1,T2>&p){
  os<<p.first<<" "<<p.second;
  return os;
}
template<typename T1,typename T2>
istream &operator>>(istream &is,pair<T1,T2>&p){
  is>>p.first>>p.second;
  return is;
}
template<typename T>
istream &operator>>(istream &is,vector<T> &a){
  for(auto &i:a)is>>i;
  return is;
}
#define reps(i,a,n) for(int i=(a);i<(n);i++)
#define rep(i,n) reps(i,0,n)
#define all(x) x.begin(),x.end()
ll myceil(ll a,ll b){return (a+b-1)/b;}
using mint=modint1000000007;
mint comb(int x,int y){
  mint ret=1;
  rep(i,x)ret*=i+1;
  rep(i,y)ret/=i+1;
  rep(i,x-y)ret/=i+1;
  return ret;
}
int main(){
  //FILE *in=freopen("input.text","r",stdin);
  int m;
  cin>>m;
  vector<ll>h;
  ll x,sum=0;
  while(cin>>x){
    h.push_back(x);
    sum+=x;
  }
  int n=h.size();
  if(n==1&&h[0]==0)cout<<1<<endl;
  else if(sum+n-1>m)cout<<"NA"<<endl;
  else{
    m-=sum;
    m-=n-1;
    mint ans=comb(n+m,m);
    cout<<ans.val()<<endl;
  }
}