Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
	)

var scanner = bufio.NewScanner(os.Stdin)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		n, _ := strconv.Atoi(buf[0])
		x, _ := strconv.Atoi(buf[1])
		prime_table := make([]int, 1000001)
		prime_table[0] = -1
		prime_table[1] = -1
		for i := 2; i < 1000001; i++ {
			if prime_table[i] != -1 {
				prime_table[i] = 1
				for j := 2*i; j < 1000001; j += i {
					prime_table[j] = -1 // -1 means "not prime"
				}
			}
		}
		dp := make([]int, x+1)
		dp[0] = 1
		menu := make([]int, n)
		for i := 0; i < n; i++ {
			scanner.Scan()
			menu[i], _ = strconv.Atoi(scanner.Text())
		}
		for i := 0; i < n; i++ {
			for j := 0; j <= x; j++ {
				if menu[i] <= j && dp[j-menu[i]] != 0 {
					// log.Println(dp)
					dp[j] = 1
				}
			}
		}
		flag := true
		for j := x; j >= 0; j-- {
			if prime_table[j] == 1 && dp[j] == 1 {
				flag = false
				fmt.Println(j)
				break
			}
		}
		if flag {
			fmt.Println("NA")
		}
	}
}

C++: #include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <complex>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
using namespace std;
typedef pair<int,int> P;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 2000000000
#define EQ(a,b) (abs((a)-(b))<EPS)
#define Max_N 1000010
bool prime[Max_N];
int menu[30];
bool dp[Max_N];
void eratos()
{
	fill(prime,prime+Max_N,true);
	prime[0]=false;
	prime[1]=false;
	for(int i=2;i*i<Max_N;i++)
	{
		if(prime[i])
		{
			for(int j=2*i;j<Max_N;j+=i)
			{
				prime[j]=false;
			}
		}
	}
	return;
}
int main()
{
	fill(dp,dp+Max_N,false);
	eratos();
	while(1)
	{
		int n,x;
		cin >> n >> x;
		if(n==0&&x==0)break;
		for(int i=0;i<n;i++)
		{
			cin >> menu[i];
		}
		dp[0]=true;
		int ans=0;
		for(int i=1;i<=x;i++)
		{
			for(int j=0;j<n;j++)
			{
				if(i-menu[j]>=0&&dp[i-menu[j]])
				{
					dp[i]=true;
                                        break;
				}
			}
			if(prime[i]&&dp[i])
			{
				ans=i;
			}	
		}
		if(ans!=0)
		{
			cout << ans << endl;
		}
		else
		{
			cout << "NA" << endl;
		}
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <cmath>
#include <queue>
#include <functional>

using namespace std;

int main() {
	int n, x;
	vector<int> furui(1000000+1, 0);
	furui[0] = furui[1] = 1;
	for (int i = 2; i*i <= 1000000; i++) {
		if (furui[i] == 0) {
			for (int j = 2; i*j <= 1000000; j++) {
				furui[i*j] = 1;
			}
		}
	}
	while (cin >> n >> x) {
		if (n == 0 && x == 0) {
			break;
		}
		vector<int> en;
		priority_queue<int, vector<int>, greater<int> > pq;
		vector<int> dp(x+1, 0);
		for (int i = 0; i < n; i++) {
			int k;
			cin >> k;
			dp[k] = 1;
			pq.push(k);
		}
		en.push_back(pq.top());
		pq.pop();
		while (!pq.empty()) {
			int k = pq.top();
			pq.pop();
			bool hantei2 = true;
			for (int i = 0; i < en.size(); i++) {
				if (k % en[i] == 0) {
					hantei2 = false;
					break;
				}
			}
			if (hantei2) {
				en.push_back(k);
			}
		}
		for (int i = 0; i < en.size(); i++) {
			for (int j = 0; j <= x; j++) {
				if (j < en[i]) {
				} else {
					dp[j] = max(dp[j], dp[j-en[i]]);
				}
			}
		}
		bool hantei = true;
		for (int i = x; i >= 0; i--) {
			if (dp[i] > 0 && furui[i] == 0) {
				cout << i << endl;
				hantei = false;
				break;
			}
		}
		if (hantei) {
			cout << "NA" << endl;
		}
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,l,n) for(int i=l;i<n;i++)
#define all(a) a.begin(),a.end()
#define o(a) cout<<a<<endl
#define int long long
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;

bool is_prime(int n){
	if(n<=1) return false;
	for(int i=2;i*i<=n;i++){
		if(n%i==0) return false;
	}
	return true; 
}

bool dp[1000100];

signed main(){
	int n,m;
	while(1){
		cin>>n>>m;
		if(n+m==0) break;
		vi a(n);
		rep(i,0,n) cin>>a[i];
		//memset(dp,false,sizeof(dp));
		rep(j,0,m+1) dp[j]=false;
		dp[0]=true;
		rep(i,0,n){
			rep(j,0,m+1){
				if(dp[j] && j+a[i]<=m){
					dp[j+a[i]]=true;
				}
			}
		}
		int ans=-1;
		for(int i=m;i>=0;i--){
			//if(dp[i]) o(i);
			if(dp[i] && is_prime(i)){
				ans=i;
				break;
			}
		}
		if(ans==-1) o("NA");
		else o(ans);
	}
}

C++: #include <iostream>
#include <vector>
#include <list>
#include <map>
#include <cmath>

using namespace std;

vector<int> price;
list<int> primes;

const int M = 1000000;
const int L = 30;
const int D = 7;
const int S = M/D;
pair<int,int> memo[S][L];

void mk_primes(int x)
{
	for( int i = 3; i <= x; i+=2 ) {
		for( int j = 3; j <= sqrt(i); j++ ) {
			if( i % j == 0 ) {
				goto NEXT;
			}
		}
		primes.push_front(i);
	NEXT:;		
	}
}

int solve(int x, int pos)
{
	pair<int,int>& pa = memo[x%S][pos];
	if( pa.first == x && -1 < pa.second )
		return pa.second;

	int result = 0;

	int p = price[pos++];
	int s = x / p;

	if( price.size() == pos ) {

		if( s*p == x ) {
			result = 1;
			// cout << "(" << p << "*" << s << ")";
		}
		
		
	} else {

		for( int i = 0; i <= s; i++ ) {

			int t = i * p;
			result = solve(x-t, pos);
			if( result ) {
				// cout << "(" << p << "*" << i << ")";
				break;
			}
		}
	}

	pa.first = x;
	pa.second = result;
	return result;
}

int main(int argc, char* argv[])
{
	while(1) {

		int n; cin >> n;
		int x; cin >> x;

		if( n == 0 && x == 0)
			break;
	
		for( int i = 0; i < n; i++ ) {
			int p; cin >> p;
			price.push_back(p);
		}

		mk_primes(x);

		for( int i = 0; i < S; i++ ) {
			for( int j = 0; j < L; j++ ) {			
				memo[i][j] = make_pair(-1,-1);
			}
		}

		for( auto p : primes ) {
			if( solve(p, 0) ) {
				cout << p << endl;
				goto LAST;
			}
		}

		cout << "NA" << endl;

	LAST:;

		price.clear();

	}

    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <utility>
#include <set>
#include <cmath>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
#define pi acos(-1)
#define all(v) v.begin(),v.end()
#define EPS (1e-10)
#define EQ(a,b) (abs((a)-(b))<EPS)
#define EQV(a,b) (EQ((a).real(),(b).real()) && EQ((a).imag(),(b).imag()))
using namespace std;
typedef pair<int,int> point;
typedef complex<double> P;
typedef long long ll;

const double eps = 1e-8;
const double INF = 1e12;


double dot(P a,P b){
	return a.real()*b.real()+a.imag()*b.imag();
}
double cross(P a,P b){
	return a.real()*b.imag()-a.imag()*b.real();
}

bool is_orthogonal(P a1,P a2,P b1,P b2){
	return EQ(dot(a1-a2,b1-b2),0.0);
}
bool is_parallel(P a1,P a2,P b1,P b2){
	return EQ(cross(a1-a2,b1-b2),0.0);
}

bool is_point_on_line(P a,P b,P c){
	return EQ(cross(b-a,c-a),0.0);
}

bool is_point_on_linesegment3(P a,P b,P c){
	return (abs(a-c)+abs(c-b)<abs(a-b)+EPS);
}

double distance_l_p(P a,P b,P c){
	return abs(cross(b-a,c-a))/abs(b-a);
}


double distance_ls_p(P a,P b,P c){
	if(dot(b-a,c-a)<EPS)return abs(c-a);
	if(dot(a-b,c-b)<EPS)return abs(c-b);
	return abs(cross(b-a,c-a))/abs(b-a);
}

bool prime[1000001];

int main(){
	int n,x;
	rep(i,1000001)prime[i]=true;
	prime[0]=prime[1]=false;
	for(int i=2;i<1001;i++){
		for(int j=2;i*j<1000000;j++){
			prime[i*j]=false;
		}
	}
	while(1){
		cin>>n>>x;
		if(n==0 && x==0)break;
		int menu[n];
		rep(i,n)cin>>menu[i];
		bool cost[1000001];
		rep(i,1000001)cost[i]=false;
		cost[0]=true;
		rep(i,x+1){
			if(cost[i]){
				rep(j,n)if(i+menu[j]<=x)cost[i+menu[j]]=true;
			}
		}
		bool check=true;
		for(int i=x;i>=2;i--){
			if(cost[i]==1 && prime[i]==1){
				cout<<i<<endl;
				check=false;
				break;
			}
		}
		if(check)cout<<"NA"<<endl;
	}
	return 0;
}