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<iostream>
#include<algorithm>
#include<queue>
using namespace std;
#define MAX 1000000

bool prime[MAX];
bool order[MAX+1];
int menu[30];
int n,money;

void init(){
	fill(prime,prime+MAX,true);
	prime[0]=prime[1]=false;
	for(int i=2;i<MAX;i++){
		if(prime[i]){
			for(int j=2;j*i<MAX;j++)
				prime[j*i]=false;
		}
	}
}
void search(){
	queue<int> que;
	int m;
	que.push(0);
	while(!que.empty()){
		m=que.front();
		que.pop();
		if(money<m || order[m])continue;
		order[m]=true;
		for(int i=0;i<n;i++)que.push(m+menu[i]);
	}
}
int main(){
	init();
	while(cin>>n>>money,n|money){
		for(int i=0;i<n;i++)cin>>menu[i];
		fill(order,order+(MAX+1),false);
		search();
		int ans=-1;
		for(int i=money;i>1;i--){
			if(prime[i] && order[i]){
				ans=i;
				break;
			}
		}
		if(ans!=-1)cout<<ans<<endl;
		else cout<<"NA"<<endl;
	}
}

C++: #include<iostream>

bool prime[1000001], dp[1000001];

int main(){
	for(int i=0;i<=1000000;i++){
		prime[i] = true;
	}
	prime[0] = prime[1] = 0;
	for(int i=2;i<=1000000;i++){
		if(prime[i]){
			for(int j=i*2;j<=1000000;j+=i)prime[j] = false;
		}
	}

	int n, x, a[30];
	while(std::cin >> n >> x, n){
		for(int i=0;i<=x;i++){
			dp[i] = false;
		}

		for(int i=0;i<n;i++){
			std::cin >> a[i];
		}

		int res = 0;

		dp[0] = true;
		for(int i=1;i<=x;i++){
			for(int j=0;j<n;j++){
				if(i-a[j] >= 0 && dp[i-a[j]]){
					dp[i] = true;
					break;
				}
			}
			if(dp[i] && prime[i]){
				res = i;
			}
		}

		if(res != 0){
			std::cout << res << std::endl;
		}else{
			std::cout << "NA" << std::endl;
		}
	}
}

C++: #include<cstdio>
#include<iostream>
#include<vector>
#include<string>
#include<map>
#include<algorithm>

using namespace std;

int main(){
	bool sosuu[1000011];
	bool dp[1000011];
	
	while(1){
		for(int i=0;i<=1000000;i++){
			sosuu[i]=0;
			dp[i]=0;
		}
		for(int i=2;i<=500000;i++){
			if(sosuu[i]==0){
				for(int j=i;j<=1000000;j+=i){
					sosuu[j]=1;
				}
				sosuu[i]=0;
			}
		}
		sosuu[0]=1;
		sosuu[1]=1;
		
		int item[30];
		
		int n,m;
		scanf("%d%d",&n,&m);
		
		if(n==0 && m==0){
			break;
		}
		for(int i=0;i<n;i++){
			scanf("%d",&item[i]);
		}
		dp[0]=1;
		for(int i=0;i<=m;i++){
			for(int j=0;j<n;j++){
				if(i<item[j]){
					continue;
				}
				if(dp[i-item[j]]==1){
					dp[i]=1;
				}
			}
		}
		int num=0;
		for(int i=m;i>=0;i--){
			if(dp[i]==1&&sosuu[i]==0){
				num=i;
				break;
			}
		}
		if(num==0){
			puts("NA");
		}else{
			printf("%d\n",num);
		}
	}
}

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

const int MX = 1000001;
int n, x;
bool tbl[MX], sieve[MX];
int v[30];

void makeSieve() {
    memset(sieve, false, sizeof sieve);
    sieve[0] = sieve[1] = true;
    for (int i=2; i*i<MX; ++i) {
        if ( ! sieve[i]) {
            for (int j=i*i; j<MX; j+=i) {
                sieve[j] = true;
            }
        }
    }
}

int main() {
    makeSieve();
    while (cin >> n >> x, n) {
        for (int i=0; i<n; ++i) {
            cin >> v[i];
        }
        for (int i=0; i<=x; ++i) {
            tbl[i] = false;
        }
        tbl[0] = true;
        for (int i=0; i<n; ++i) {
            for (int j=v[i]; j<=x; ++j) {
                tbl[j] |= tbl[j-v[i]];
            }
        }
        int ans = -1;
        for (int i=x; i>=0; --i) {
            if (tbl[i] && ! sieve[i]) {
                ans = i;
                break;
            }
        }
        if (0 < ans) {
            cout << ans << endl;
        } else {
            cout << "NA" << endl;
        }
    }
    return 0;
}

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

using namespace std;

typedef long long ll;
typedef long double ld;
typedef tuple<int, int> duo;
const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int Mod = 1000000000 + 0;
//{{{ templates
#define TT_ template<typename T>inline
#define TTF_ template<typename T,typename F>inline
TT_ T sq(T x){return x*x;}
TT_ T In(){T x;cin>>x;return x;}
TT_ void Out(T&x){cout<<x;}
TT_ void sort(T&v){sort(begin(v),end(v));}
TT_ void revs(T&v){reverse(begin(v),end(v));}
TT_ void uniq(T&v){sort(v);v.erase(unique(begin(v),end(v)),end(v));}
TT_ int ubnd(T&v,typename T::value_type x){return upper_bound(begin(v),end(v),x)-begin(v);}
TT_ int lbnd(T&v,typename T::value_type x){return lower_bound(begin(v),end(v),x)-begin(v);}
TTF_ void inpt(T&v,int n,F f){for(v.reserve(n);n--;v.emplace_back(f()));}
TTF_ void show(T&v,F f,string d=" ",string e="\n"){int i=0;for(auto&x:v)i++&&(cout<<d),f(x);cout<<e;}
TT_ typename T::iterator minel(T&v){return min_element(begin(v),end(v));}
TT_ typename T::iterator maxel(T&v){return max_element(begin(v),end(v));}

inline void fast_io(){ios_base::sync_with_stdio(0);cin.tie(0);}
inline int in(){int x;scanf("%d",&x);return x;}
inline ll pow_mod(ll a,ll k,ll m){ll r=1;for(;k>0;a=a*a%m,k>>=1)if(k&1)r=r*a%m;return r;}
inline ll mod_inv(ll a,ll p){return pow_mod(a,p-2,p);}
//}}} priority_queue queue deque front stringstream max_element min_element insert count make_tuple

const int MAX_N = 10100100;
int dp[MAX_N];
bool sieve[MAX_N];

int main()
{
  sieve[0] = sieve[1] = true;
  for (int i = 2; i * i <= MAX_N; i++){
    if (sieve[i]) continue;
    for (int j = i * i; j <= MAX_N; j += i){
      sieve[j] = true;
    }
  }

  int n, x, K = 1;
  while (n = in(), x = in(), n){
    int ans = -1;

    dp[0] = K;
    for (int i = 0; i < n; i++){
      int cost = in();
      for (int j = 0; j + cost <= x; j++){
        if (dp[j] == K){
          dp[j + cost] = K;
          if (!sieve[j + cost]) ans = max(ans, j + cost);
        }
      }
    }
    K++;
    if (ans < 0) puts("NA");
    else printf("%d\n", ans);
  }
  return 0;
}