#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
#include <fstream>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
typedef long long ll;

#define INF 1000000000
#define MOD 1000000007

// x^n mod
long mod_pow(long x, long n, long mod){
  long res=1;
  while(n>0){
    if(n&1) res=res*x%mod;
    x=x*x%mod;
    n>>=1;
  }
  return res;
}


int main(){
    int m;
    cin>>m;
    vector<int> vec;
    int d;
    int sum=0;
    while(scanf("%d", &d)!=-1){
        vec.pb(d);
        sum+=d;
    }

    if(vec[0]==0){ cout<<1<<endl; return 0;}

    int a=vec.size(), b=m-sum-(vec.size()-1);

    if(b<0){ cout<<"NA"<<endl; return 0;}

//    dbg(a);dbg(b);
    long res=1;
    for(int i=b+1;i<=a+b;i++) res = res*i%MOD;

    long tmp=1;
    for(int i=1;i<=a;i++) tmp = tmp*i%MOD;  // a!
    res = res*mod_pow(tmp, MOD-2, MOD)%MOD; // a!^(-1)

    cout<<res<<endl;

    return 0;
}