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 <string>
#include <vector>
#include <queue>
#include <bitset>
#include <set>
#include <map>
#include <stack>
#include <list>

#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,b,n) for(int i=b;i<n;i++)
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

const float PI = 3.1415926;
static const int INFTY = (1<<30);

using namespace std;

typedef long long ll;
typedef long double ld;


int n;
ll V[31], x;
ll dp[32][1LL<<32];
ll maxn;

bool sosu(ll t){
  if(t == 1) return false;
  if(t == 2) return true;
  if(t%2 == 0) return false;

  for(ll i=3; i*i<=t; i+=2){
    if(t%i == 0) return false;
  }

  return true;
}

void solve(ll now) {
  if(now > x) return;
  if(sosu(now) && now > maxn)
    maxn = now;
  rep(i, n) {
    solve(now + V[i]);
  }
  return;
}

int main() {
  while(cin >> n >> x, n) {
    maxn = 0;
    rep(i, n) {
      cin >> V[i];
    }
    solve(0);
    if(maxn == 0) {
      cout << "NA" << endl;
    } else {
      cout << maxn << endl;
    }
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 10007;
static const int INF = 1 << 25;
static const LL LL_INF = 1152921504606846976;
static const int dx[] = { -1, 0, 1, 0,  1, -1,  1, -1 };
static const int dy[] = { 0, -1, 0, 1 , 1,  1, -1, -1 };

static bool is_pm[ 10000010 ];
static bool dp[ 10000010 ];
static ull ans = 0, m;
static char n;
static vector<ull> ar;

static void solve( const ull how_much ) {
	if ( how_much > m  ) {
		return;
	}
	if ( is_pm[ how_much ] ) {
		ans = max( ans, how_much );
	}
	if ( how_much == m ) {
		return;
	}
	if ( dp[ how_much ] ) {
		return;
	}
	
	dp[ how_much ] = true;
	for ( int i = 0; i < ar.size(); i++ ) {
		solve( how_much + ar[ i ] );
	}
}

int main() {
	memset( is_pm, -1, sizeof( is_pm ) );
	for ( ull i = 2; i * i <= 10000004; i += 2 ) {
		if ( is_pm[ i ] ) {
			for ( ull j = i * i; j <= 10000004; j += i) {
				is_pm[ j ] = false;
				if ( i % 2 == 1 ) {
					j += i;
				}
			}
		}
		if ( i == 2 ) {
			--i;
		}
	}
	while ( ~scanf( "%d %d", &n, &m ) && n && m ) {
		ar.resize( n );
		for ( int i = 0; i < n; i++ ) {
			scanf( "%d", &ar[ i ] );
		}
		sort( ar.begin(), ar.end() );
		ar.erase( unique( ar.begin(), ar.end() ), ar.end() );
		sort( ar.rbegin(), ar.rend() );
		memset( dp, false, sizeof( dp ) );
		ans = 0;
		solve( 0 );
		if ( ans == 0 ) {
			printf( "NA\n" );
		}
		else {
			printf( "%d\n", ans );
		}
	}
	return 0;
}

C++: #include<iostream>
#include<string.h>
#include<vector>
#include<list>
#include<stdio.h>
#include<math.h>
#include<iomanip>
#include<map>
#include<stack>
#include<queue>
#include<algorithm>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) range(i,0,b)
#define debug(x) cout << "debug " << x << endl;
using namespace std;

int main(){
    int n, x, ord[35];
    bool prime[1000000] = {1,1,0};

    rep(i,1000000){
        if(!prime[i]){
            for(int j = i + i; j < 1000000; j+=i){
                prime[j] = 1;
            }
        }
    }

    while(cin >> n >> x, n||x){
        bool total[1000000] = {1};
        rep(i,n){
            cin >> ord[i];
        }
        rep(i,x){
            if(total[i]){
                rep(j,n){
                    if(i + ord[j] > x) continue;
                    total[i + ord[j]] = 1;
                }
            }
        }
        bool c = true;
        for(int i = x; i >= 0; i--){
            if(prime[i] == 0 && total[i] == 1){
                cout << i << endl;
                c = false;
                break;
            }
        }
        if(c) cout << "NA" << endl;
    }
}

C++: #include<iostream>
using namespace std;
#define MAX_N 1000000

int prime[MAX_N];
bool is_prime[MAX_N + 1];

int main(){

  //素数判定
  int p = 0;
  for(int i=0;i<=MAX_N;i++) is_prime[i] = true;
  is_prime[0] = is_prime[1] = false;
  for(int i=2;i<=MAX_N;i++){
    if(is_prime[i]){
      prime[p++] = i;
      for(int j=2*i;j<=MAX_N;j+=i) is_prime[j] = false;
    }
  }

  int n,x;
  while(cin >> n >> x){
    if(n==0&&x==0) break;
    int v[n];
    bool dp[x+1];
    for(int i=0;i<=x;i++)
      dp[i] = false;

    for(int i=0;i<n;i++)
      cin >> v[i];
    dp[v[0]] = true;

    for(int i=0;i<n;i++){
      for(int j=0;j<=x-v[i];j++){
        if(dp[j]) dp[j+v[i]] = true;
      }
    }
    for(int i=x;i>=0;i--){
      if(i==0) cout << "NA" << endl;
      if(dp[i]&&is_prime[i]){
        cout << i << endl;
        break;
      }
    }
  }
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
bool dp[1000120];
bool notPrime[1000120];
int main(){
    notPrime[0] = notPrime[1] = true;
    for(int i = 2;i*i < 1000010;i++){
        for(int j = 2 * i;j < 1000010;j+=i){
            notPrime[j] = true;
        }
    }
    int n,x;
    while(cin>>n>>x,n){
        dp[0] = true;
        while(n--){
            int a;
            cin>>a;
            for(int i = 0;i <= x;i++){
                if(dp[i])dp[i+a] = true;
            }
        }
        bool flg = false;
        for(int i = x;i >= 2;i--){
            if(!notPrime[i] & dp[i]){
                cout<<i<<endl;
                flg = true;
                break;
            }
        }
        if(!flg)cout<<"NA"<<endl;
        for(int i = 0;i < 1000020;i++)dp[i] = false;
    }
}