#ifdef __GNUC__
#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#endif

#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>
#include <stdio.h>

#include <sstream>
#include <algorithm>
#include <cmath>

#include <string>
#include <cstring>
#include <vector>
#include <valarray>
#include <array>

#include <queue>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <list>

#include <cassert>//assert();
#include <fstream>
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)

/////////
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
#define PII pair<int,int>
/////////
using namespace::std;

// 最大公約数
template<class T>
inline T gcd(T a, T b){return b == 0 ? a : gcd(b, a % b);}
// 最小公倍数
template<class T>
inline T lcm(T a, T b){return a * b / gcd(a, b);}
////////////////////////////////
const ULL mod = 1000000007;
ULL inv[1000010];
ULL invMod(ULL k){//k**(mod-2)
//  098765432109876543210987654321
//0b111011100110101100101000000111
	ULL p = mod-2;
	ULL ret = 1;
	while(p){//30回回る
		if( p & 1 ){
			ret = (ret*k)%mod;
		}
		k = (k*k)%mod;
		p >>= 1;
	}
	return ret;
}

ULL nCk(ULL N,ULL k){
	k = min(k,N-k);
	if( k == 0 ){return 1;}
	if( k == 1 ){return N%mod;}
	ULL ret = 1;
	for(int i=1;i<=k;++i){
		ret *= (N+1-i);//OVF
		ret %= mod;
	}
	ULL kkai = 1;
	for(int i=1;i<=k;++i){
		kkai *= i;
		kkai %= mod;
	}
	ret = ( ret*invMod(kkai) ) %mod;
	return ret;
}

inline void solve(){
	int N;
	scanf("%d",&N);
	int temp	= 0;
	int sum		= 0;
	int kind	= 0;

	while( scanf("%d",&temp) != EOF ){
		sum += temp;
		++kind;
	}
	if( sum == 0 ){
		printf("1\n");
		return;
	}
	if( sum + kind-1 > N ){
		printf("NA\n");
		return;
	}
	int aki = N - (sum+kind-1);
	printf("%d\n", nCk(aki+kind,kind) );
}

int main(void){
	//std::cin.tie(0);
	//std::ios::sync_with_stdio(false);
	//std::cout << std::fixed;//小数を10進数表示
	//cout << setprecision(16);//小数をいっぱい表示する。16?

	solve();

	return 0;
}