#include <iostream>
#include <vector>
#include <map>
#include <cmath>
using namespace std;
const long long MAX = 10000000;
const long long MOD = 1000000007;
long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (long long i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        //そのまま計算すると負の値になるのでMODを足す
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
// 二項係数計算
long long COM(long long n, long long k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}


int main() {
    COMinit();
    long long n;
    cin >> n;
    long long asize = 1;
    long long a = n;
    while(cin >> n) {
        if(n==0) continue;
        asize+=1;
        a-=n;
    }
    if(asize >= 3 && a-asize+2 < 0) cout << "NA" << endl;
    else cout << COM(a+1, a-asize+2) << endl;
}