#include<bits/stdc++.h>
#define Add(x,y) (x+y>=mod)?(x+y-mod):(x+y)
#define lowbit(x) x&(-x)
#define pi pair<ll,ll>
#define pii pair<ll,pair<ll,ll>>
#define iip pair<pair<ll,ll>,ll>
#define ppii pair<pair<ll,ll>,pair<ll,ll>>
#define fi first
#define se second
#define full(l,r,x) for(auto it=l;it!=r;it++) (*it)=x
#define Full(a) memset(a,0,sizeof(a))
#define open(s1,s2) freopen(s1,"r",stdin),freopen(s2,"w",stdout);
#define For(i,l,r) for(int i=l;i<=r;i++)
#define _For(i,l,r) for(int i=r;i>=l;i--)
using namespace std;
typedef double db;
typedef unsigned long long ull;
typedef long long ll;
bool Begin;
const ll N=2e6+10,mod=1e9+7;
inline ll read(){
    ll x=0,f=1;
    char c=getchar();
    while(c<'0'||c>'9'){
        if(c=='-')
          f=-1;
        c=getchar();
    }
    while(c>='0'&&c<='9'){
        x=(x<<1)+(x<<3)+(c^48);
        c=getchar();
    }
    return x*f;
}
inline void write(ll x){
	if(x<0){
		putchar('-');
		x=-x;
	}
	if(x>9)
	  write(x/10);
	putchar(x%10+'0');
}
ll n,x,sum,k;
ll f[N],inv[N];
ll qpow(ll a,ll b){
	ll ans=1;
	while(b){
		if(b&1)
		  ans=(ans*a)%mod;
		a=(a*a)%mod;
		b>>=1ll;
	}
	return ans;
}
void init(){
	f[0]=f[1]=inv[0]=inv[1]=1;
	For(i,2,N-1)
	  f[i]=(f[i-1]*i)%mod;
	inv[N-1]=qpow(f[N-1],mod-2);
	_For(i,2,N-2)
	  inv[i]=inv[i+1]*(i+1)%mod;
}
ll C(ll n,ll m){
	return f[n]*inv[m]%mod*inv[n-m]%mod;
}
bool End;
int main(){
//	open("banner.in","banner.out");
	init();
	n=read();
	while(scanf("%lld",&x)!=EOF){
		++k;
		sum+=x;
	}
	sum=n-sum-k+1;
	if(sum<0){
		puts("NA");
		exit(0);
	}
	if(k==1&&!x){
		puts("1");
		exit(0);
	}
	write(C(sum+k,k));
	cerr<<'\n'<<abs(&Begin-&End)/1048576<<"MB";
	return 0;
}