#include <iostream>
using namespace std;

int p=1000000007;

/*
int mod_comb(int n,int k,int p){
    if(n<0||k<0||n<k)return 0;
    if(k==0)return 1;
    return (mod_comb(n-1,k,p)+mod_comb(n-1,k-1,p))%p;
}*/

int extgcd(int a, int b, int&x, int&y){
    int d=a;
    if(b!=0){
        d=extgcd(b,a%b,y,x);
        y-=(a/b)*x;
    }else{
        x=1;y=0;
    }
    return d;
}

int mod_inverse(int a, int m){
    int x, y;
    extgcd(a,m,x,y);
    return (m+x%m)%m;
}

int fact(int n, int p){
    long long int res=1;
    while(n){
        res*=n;
        if(res>p)res%=p;
        if(res==0)return 0;
        n--;
    }
    return (int)res;
}

int mod_fact(int n,int p,int &e){
    e=0;
    if(n==0)return 1;
    int res=mod_fact(n/p,p,e);
    e+=n/p;
    if(n/p%2!=0) return res*(p-fact(n%p,p))%p;
    return res*fact(n%p,p)%p;
}

int mod_comb(int n, int k,int p){
    if(n<0||k<0||n<k)return 0;
    int e1,e2,e3;
    long long int a1=mod_fact(n,p,e1),a2=mod_fact(k,p,e2),a3=mod_fact(n-k,p,e3);
    if(e1>e2+e3)return 0;
    return (a1*mod_inverse(a2*a3%p,p))%p;
}

int main(){
    int M;
    cin>>M;
    int count=0, black=0, part;
    while(cin>>part){
        count++;
        black+=part;
    }
    if(M<black+count-1)cout<<"NA"<<endl;
    else
    //M-black-(count-1)個のwhileをcount+1個に分割する。(M-black+count)C(count)
    //cout<<mod_comb(5,3,p)<<endl;
    //cout<<M-black+1<<' '<<count<<endl;
    //cout<<fact(M-black+1,p)<<endl;
    cout<<mod_comb(M-black+1,count,p)<<endl;

    return 0;
}