#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>

#define REP(i,n) for(long (i)=0;(i)<(n);(i)++)
#define FOR(i,a,b) for(long (i)=(a);(i)<(b);(i)++)
#define RREP(i,a) for(long (i)=(a)-1;(i)>=0;(i)--)
#define FORR(i,a,b) for(long (i)=(a)-1;(i)>=(b);(i)--)
#define MOD 1000000007
#define PI acos(-1.0)
#define DEBUG(C) cout<<C<<endl;
#define VI vector<int>
#define VL vector<long>
#define VD vector<double>
#define PII pair<int,int>
#define PDD pair<double,double>
#define PLL pair<long,long>
#define ALL(a) (a).begin(),(a).end()
#define SORT(a) sort(ALL(a))
#define REVERSE(a) reverse(ALL(a))
#define MP make_pair
#define FORE(a,b) for(auto &&a:b)

typedef long long LL;
typedef unsigned long long ULL;

using namespace std;

#define long LL
long pow_mod(long a,long p){
    if(p==0) return 1;
    if(p&1) return a*pow_mod(a,p-1)%MOD;
    long t=pow_mod(a,p/2)%MOD;
    return t*t%MOD;
}

int main(void){
    int M; cin>>M; vector<int> v;
    int in; while(cin>>in){
        if(in==0) break;
        v.emplace_back(in);
    }
    int sum=accumulate(ALL(v),0);
    if(v.size()==1 && v.front()==0){
        cout<<1<<endl; return 0;
    }
    if(v.size()==1 && v[0]==M){
        cout<<1<<endl; return 0;
    }
    if(M-sum<v.size()-1){
        cout<<"NA"<<endl; return 0;
    }
    long ans=1;
    REP(i,v.size()){
        if(i==0 || i==v.size()-1) ans*=(M-sum+1);
        else ans*=(M-sum);
        ans%=MOD;
    }
    long buf=pow_mod(v.size()+1,MOD-2);
    cout<<ans*buf%MOD<<endl;
    return 0;
}