#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

template<int MOD>
class ModInt{
public:
    ModInt():value(0){}
    ModInt(int val):value(val<0?MOD+val%MOD:val%MOD){ }
    
    ModInt& operator+=(ModInt that){
        value = value+that.value;
        if(value>=MOD)value-=MOD;
        return *this;
    }
    ModInt& operator-=(ModInt that){
        value -= that.value;
        if(value<0)value+=MOD;
        return *this;
    }
    ModInt& operator*=(ModInt that){
        value = (int)((long long)value * that.value % MOD);
        return *this;
    }
    ModInt &operator/=(ModInt that){
        return *this *= that.inverse();
    }
    ModInt operator+(ModInt that) const{
        return ModInt(*this)+=that;
    }
    ModInt operator-(ModInt that) const{
        return ModInt(*this)-=that;
    }
    ModInt operator*(ModInt that) const{
        return ModInt(*this)*=that;
    }
    ModInt operator/(ModInt that) const {
        return ModInt(*this) /= that;
    }
    ModInt operator^(long long k) const{
        ModInt n = *this, res = 1;
        while(k){
            if(k & 1)res *= n;
            n *= n;
            k >>= 1;
        }
        return res;
    }
    ModInt inverse() const {
        long long a = value, b = MOD, u = 1, v = 0;
        while(b) {
            long long t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        return ModInt(u);
    }
    int toi() const{ return value; }

private:
    int value;
};
typedef ModInt<1000000007> mint;
ostream& operator<<(ostream& os, const mint& x){
    os << x.toi();
    return os;
}

/*
n個のものからr個選ぶ場合の数
O(n+r)
*/
mint nCr(int n, int r){
    mint res = 1;
    for(int i = 2; i <= n; ++i)
        res *= i;
    for(int i = 2; i <= n - r; ++i)
        res /= i;
    for(int i = 2; i <= r; ++i)
        res /= i;
    return res;
}

/*
n個のものから「重複を許して」r個選ぶ場合の数
O(n+r)
*/
mint nHr(int n, int r){
    return nCr(n + r - 1, r);
}

int main(){
    int N;
    cin >> N;
    vi a;
    int x;
    while(~scanf("%d", &x)){
        a.push_back(x);
    }
    if(sz(a) == 1 && (a[0] == 0 || a[0] == N)){
        puts("1");
        return 0;
    }

    int sum = -1;
    each(y, a){
        sum += y + 1;
        if(sum > N){
            puts("NA");
            return 0;
        }
    }

    mint ans = nHr(sz(a) + 1, N - sum);
    cout << ans << endl;
}