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])
		if n == 0 && x == 0 {
			break
		}
		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 <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstring>
using namespace std;

#define MAX_X 1000001

int n;
int x;
vector<int> p;

bool table[MAX_X];
vector<int> prime;

void init() {
    memset(table, 1, sizeof(table));
    table[0] = table[1] = false;
    for (int i = 2; i < MAX_X; i++) {
        if (table[i]) {
            prime.push_back(i);
            for (int j = i + i; j < MAX_X; j += i) {
                table[j] = false;
            }
        }
    }
}

bool cache[MAX_X];
bool cached[MAX_X];

bool can_make(int t) {
//    cout << t << endl;
    if (t == 0) return true;
    else if (t < 0) return false;
    if (cached[t]) return cache[t];

    bool can = false;
    for (int i = 0; i < p.size(); i++) {
        if (can_make(t-p[i])) {
            can = true;
            break;
        }
    }
    cache[t] = can;
    cached[t] = true;
    return can;
}

int main() {
    init();
//    for (int i = 0; i < prime.size(); i++) {
//        cout << prime[i] << ' ';
//    }

    while (cin >> n >> x, n || x) {
        memset(cache, 0, sizeof(cache));
        memset(cached, 0, sizeof(cached));

        p.clear();
        p.resize(n);
        for (int i = 0; i < n; i++) {
            cin >> p[i];
        }
        sort(p.begin(), p.end(), greater<int>());

        bool exist = false;

        int ub = prime.size()-1;
        int lb = 0;
        int mid;

        while (lb != ub - 1) {
            mid = (lb + ub) / 2;
            if (prime[mid] < x) {
                lb = mid;
            } else {
                ub = mid;
            }
        }

//        cout << "ub: " << ub << endl;
        for (int i = mid; 0 <= i; i--) {
            if (can_make(prime[i])) {
                cout << prime[i] << endl;
                exist = true;
                break;
            }
        }

        if (!exist) {
            cout << "NA" << endl;
        }

    }
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#define rep(i, a, n) for(int i = a;i < n;i++)
using namespace std;


int n, x;
int m[40];
int dp[40][1000010];
vector<int> prime;


void makeList(){
	rep(i, 1, n+1){
		rep(j, 0, x+1){
			if(1 < dp[i][j] && dp[i][j] <= x)
				prime.push_back(dp[i][j]);
		}
	}
}


void sieve(){
	makeList();
	for(int i = 2;i*i <= x;i++){
		prime.erase(remove_if(prime.begin(), prime.end(), [&](int v){ return (v % i == 0); }), prime.end());
	}
	sort(prime.begin(), prime.end());
}


void makeDP(){
	rep(i, 1, n+1){
		rep(j, 0, x+1){
			if(j - m[i] >= 0) dp[i][j] = max(dp[i-1][j], dp[i][j - m[i]] + m[i]);
			else dp[i][j] = dp[i-1][j];
		}
	}
}


int main(){
	while(cin >> n >> x, n || x){
		rep(i, 1, n+1) cin >> m[i];

		makeDP();

		sieve();

		if(prime.size()) cout << prime.back() << endl;
		else cout << "NA" << endl;
	}

	return 0;
}

C++: #include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

// nまでの素数のリストを作成(nを含む) O(N log log N)
vector<bool> make_prime_list(int n) {
    vector<bool> is_prime(n + 1, true);
    is_prime[0] = false;
    is_prime[1] = false;

    vector<int> prime_list;
    for (int i = 2; i < n + 1; ++i) {
        if (!is_prime[i]) { continue; }
        prime_list.emplace_back(i);

        for (int j = i + i; j < n + 1; j += i) {
            is_prime[j] = false;
        }
    }
//    return prime_list;  // 素数のリスト
    return is_prime;  // すべての数値について素数かどうか
}

int main() {
    cin.tie(0);
	ios::sync_with_stdio(false);

	auto prime_list = make_prime_list(1000001);
	prime_list[1] = true;

	while (true) {
        int n, x;
        cin >> n >> x;
        if (n == 0 or x == 0) {
            break;
        }

        vector<int> items;
        FOR(i, 0, n) {
            int p;
            cin >> p;
            items.emplace_back(p);
        }

        vector<bool> dp(x + 10, false);
        dp[0] = true;

        FOR(i, 0, n) {
            int p = items[i];
            FOR(j, 0, dp.size()) {
                if (dp[j] and j + p < dp.size()) {
                    dp[j + p] = true;
                }
            }
        }

        int ans = -1;
        FOR(i, 0, x + 1) {
            if (prime_list[i] and dp[i]) {
                ans = max(ans, i);
            }
        }

        if (ans == -1) {
            print("NA");
        }
        else {
            print(ans);
        }
    }

	return 0;
}