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<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#include<set>
#include<complex>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define CC puts("-------ok--------");
#define all(in) in.begin(), in.end()
#define bv vector<bool>
using namespace std;
typedef pair<int, int> PI;
#define MAX 1000009
ll m=0; int n=0; int ans=0;
bool flag;
int main(){
    vector<bool>check(MAX+1);  //index number will be checked
    rep(i, MAX+1)check[i] = true;
    vector<int>Primenumber(MAX+1,0); //Primearray
    int counter =0;                  //Primearray counter;
    for(int i = 2; i<MAX+1;i++){
        if(check[i]){
            for(int j = 2;i*j<MAX;j++)
                check[i*j] = false;//?´???°??????Primearray???????´??????????????????°?????¨???false???
            Primenumber[counter] = i;
            counter++;
        }
    }
    while(cin>>n>>m,n+m){
        vi v;
        int temp;
        flag=false;
        rep(i,n){cin>>temp; v.push_back(temp);}
        for(int i=(int)m;i>=0;i--){
            if(check[i]){
                ans=i;break;}
        }
        bool array[MAX]; rep(i,MAX)array[i]=false;
        rep(i,n)array[v[i]]=true;
        for(int i=1;i<=ans;i++) {
            if(array[i])rep(j,n)if(i+v[j]<=ans)array[i+v[j]]=true;
            if(array[ans])break;
        }
        flag=array[ans];
        if(flag) cout<<ans<<endl;
        else cout<<"NA"<<endl;
    }
}

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

constexpr int MAX_X = 1000000, MAX_N = 30;

int value[MAX_N], n, x;
bool dp[MAX_X + 1];
bool is_prime_number[MAX_X + 1];

void initialize();

void solve();

int main(){
    initialize();

    while(true){
        std::cin >> n >> x;
        if(n == 0 && x == 0){
            break;
        }
        
        memset(dp, false, x + 1);

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

        solve();
    }
    return 0;
}

void solve(){
    int ans = 0;

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

                    if(is_prime_number[i]){
                        ans = std::max(ans, i);
                    }

                    break;
                }
            }
        }
    }

    if(ans){
        std::cout << ans << std::endl;
    }
    else{
        std::cout << "NA" << std::endl;
    }
}

void initialize(){
    memset(is_prime_number, true, MAX_X + 1);

    is_prime_number[0] = false, is_prime_number[1] = false;
    for(int i = 2; i * i < MAX_X + 1; ++i){
        if(is_prime_number[i]){
            for(int j = 2; i * j < MAX_X + 1; ++j){
                is_prime_number[i * j] = false;
            }
        }
    }
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define forever for (;;)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
template<typename A> using V = std::vector<A>;
template<typename A> using F = std::function<A>;
template<typename A, typename B> using P = std::pair<A, B>;
using pii = P<int, int>;
using vi = V<int>;
using vd = V<double>;
using vs = V<std::string>;
using vpii = V<pii>;
using vvi = V<vi>;
using vvpii = V<vpii>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
template<typename T> std::istream &operator>>(std::istream &is, std::vector<T> &v) { for (T &x : v) is >> x; return is; }
template<typename A, typename B> std::istream &operator>>(std::istream &is, std::pair<A, B> &p) { is >> p.first; is >> p.second; return is; }
using namespace std;
// clang-format on

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

main {
  int n, x;
  while (cin >> n >> x, n) {
    vi v(n);
    cin >> v;
    vi dp(x + 1);
    dp[0] = true;
    for (auto &t : v) rep(i, x + 1 - t) dp[i + t] |= dp[i];
    for (int i = x; i > 0; i--) {
      if (dp[i] && isPrime(i)) {
        cout << i << endl;
        goto next;
      }
    }
    cout << "NA" << endl;
  next:;
  }
}

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

using namespace std;

#define LOG(...) fprintf(stderr,__VA_ARGS__)
//#define LOG(...)
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))

typedef long long ll;
typedef unsigned long long ull;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

bool sieve[1000001];
bool dp[1000001];

int main() {
    sieve[0] = sieve[1] = true;
    FOR(i, 2, 1000001) {
        if (sieve[i]) continue;
        for (int j = i + i; j < 1000001; j += i) {
            sieve[j] = true;
        }
    }

    int n, money;
    while (cin >> n >> money, n|money) {
        fill_n((bool *)dp, 1000001, false);
        dp[0] = true;
        REP(i, n) {
            int food;
            cin >> food;
            REP(j, money-food+1) {
                if (dp[j]) dp[j+food] = true;
            }
        }
        for (int i = money; i >= 0; i--) {
            if (!sieve[i] && dp[i]) {
                cout << i << endl;
                goto END;
            }
        }
        cout << "NA" << endl;
END: {}
    }
}