#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repp(i, n) rep(i, 0, n)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;
typedef pair<int, int> P;

const int mod = 1e9 + 7;
int n;

typedef long long ll;
ll mod_pow(ll x,ll n){
	if(n==0) return 1;
	ll res=mod_pow(x*x%mod,n/2);
	if(n&1) res=res*x%mod;
	return res;
}
ll fact[2000010];
ll get_nCk(ll n,ll k,ll mpd){
	fact[0]=1;
	for(int i=1;i<200010;i++) fact[i]=fact[i-1]*i%mod;
	return fact[n]*mod_pow(fact[k],mod-2)%mod*mod_pow(fact[n-k],mod-2)%mod;
}

signed main(){
    cin >> n;
    vector<int> h;
    int a, sum = 0, cnt = 0;
    while(cin >> a){
        sum += a;
        cnt++;
    }
    int ans = 0;
    int r = n - (sum + cnt - 1);
    if(sum == 0) cout << 1 << endl;
    else if(r < 0) cout << "NA" << endl;
    else{
        ans = get_nCk(r + cnt, cnt, mod);
        cout << ans << endl;
    }
}