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] != 0 {
				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 "bits/stdc++.h"

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;

#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back

bool isp(int n){
    if(n==2)return true;
    if(n==1)return false;
    if(n==0)return false;

    for(int i=2;i<=sqrt(n);i++){
        if(n%i==0)return false;
    }
    return true;
}

int main(){
    int n,x;
    while(cin>>n>>x){
        if(n==0&&x==0)break;
        
        int data[40];
        rep(i,n){
            cin>>data[i];
        }
        
        bool dp[1000001]={};
        rep(i,1000001)dp[i]=false;
        
        dp[0]=true;
        

        for(int i=1;i<=n;i++){
            for(int j=0;j<=x;j++){
//                dp[i][j] = dp[i-1][j];
                if(j-data[i-1]>=0)
                    dp[j] |= dp[j-data[i-1]];

            }
        }
        int ans = -1;
        for(int i=x;i>=0;i--){
            if(dp[i]==true){
                if(isp(i)){
                    ans=i;
                    break;
                }
            }
        }
        if(ans==-1)cout<<"NA"<<endl;
        else cout<<ans<<endl;
        
    }
}

C++: #include <iostream>
#include <vector>
using namespace std;

#define MAX_P 1000001

int main(){
	bool prime[MAX_P];
	prime[0] = false;
	prime[1] = false;
	for( int i = 2; i < MAX_P; i++ ) prime[i] = true;
	for( int i = 2; i < MAX_P; i++ ){
		if( prime[i] ){
			for( int j = 2*i; j < MAX_P; j += i ){
				prime[j] = false;
			}
		}
	}
	int n, x;
	while( cin >> n >> x, n || x ){
		vector<bool> dp(x+1);
		for( int i = 0; i <= x; i++ ) dp[i] = false;
		vector<int> p(n);
		for( int i = 0; i < n; i++ ){
			cin >> p[i];
		}
		dp[0] = true;
		int max = 0;
		for( int i = 0; i < n; i++ ){
			for( int j = p[i]; j <= x; j++ ){
				if( dp[j-p[i]] ){
					dp[j] = true;
					if( prime[j] && max < j ) max = j;
				}
			}
		}
		if( max > 0 ) cout << max << endl;
		else cout << "NA" << endl;
	}
	return 0;
}

C++: #include <cmath>
#include <iostream>

#define rep(i, n) for (int i = 0; i < n; i++)

bool is_prime(int n) {
    if (n % 2 == 0) return false;
    for (int i = 3; i <= std::sqrt(n); i += 2)
        if (n % i == 0) return false;
    return true;
}

int main() {
    int n, x;
    while (std::cin >> n >> x && n > 0 && x > 0) {
        auto course = new bool[x + 1]();
        rep(i, x + 1) course[i] = false;

        int prices[n];
        rep(i, n) { std::cin >> prices[i]; }
        course[0] = true;

        int max = -1;
        rep(i, x + 1) rep(j, n) {
            if (i - prices[j] >= 0 && course[i - prices[j]]) {
                if (is_prime(i)) max = i;
                course[i] = true;
                break;
            }
        }
        if (max < 0)
            std::cout << "NA" << std::endl;
        else
            std::cout << max << std::endl;
        delete[] course;
    }
}

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;/*
			if (k > x || k == 0) {
				continue;
			}
			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 <cmath>
#include <iostream>

#define rep(i, n) for (int i = 0; i < n; i++)

bool is_prime(int n) {
    if (n % 2 == 0) return false;
    for (int i = 3; i <= std::sqrt(n); i += 2)
        if (n % i == 0) return false;
    return true;
}

int main() {
    int n, x;
    while (std::cin >> n >> x && n > 0 && x > 0) {
        bool course[x + 1];
        rep(i, x + 1) course[i] = false;

        int prices[n];
        rep(i, n) {
            std::cin >> prices[i];
            course[prices[i]] = true;
        }

        int max = -1;
        rep(i, x + 1) rep(j, n) {
            if (i - prices[j] > 0 && course[i - prices[j]]) {
                if (is_prime(i)) max = i;
                course[i] = true;
            }
        }
        if (max < 0)
            std::cout << "NA" << std::endl;
        else
            std::cout << max << std::endl;
    }
    return EXIT_SUCCESS;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<set>
using namespace std;
int n, x, ans;
int in[31], in2[31];
bool dp[1000001];
void solve(int a, int sum){
	for (int i = a; i <= n; i++){
		if (sum + in[i] > x&&!in2[i]){
			in[i] /= 10;
			in2[i] = 1;
		}
		if (sum + in[i] <= x){
			if (dp[sum + in[i]])
				continue;
			if (sum + in[i] % 2){
				dp[sum + in[i]] = 1;
			}
			solve(i, sum + in[i]);
		}
	}
}
int main(){
	while (cin >> n >> x&&n&&x){
		ans = 0;
		fill(dp, dp + 1000001, 0);
		for (int i = 1; i <= n; i++){
			cin >> in[i];
			in[i] *= 10;
			in2[i] = 0;
		}
		solve(1, 0);
		for (int i = x; i > 0; i--){
			if (dp[i]){
				for (int j = 5; j <= x; j++){
					if (j == i)
						ans = j;
					if (i % j == 0)
						break;
				}
				if (ans)
					break;
			}
		}
		if (ans)
			cout << ans << endl;
		else
			cout << "NA" << endl;
	}
	return 0;
}