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<map>
#include<set>
#include<list>
#include<cmath>
#include<queue>
#include<stack>
#include<cstdio>
#include<string>
#include<vector>
#include<complex>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<numeric>
#include<sstream>
#include<iostream>
#include<algorithm>
#include<functional>

#define MP make_pair
#define PB push_back
#define ALL(x) (x).begin(),(x).end()
#define REP(i,n) for(int i=0;i<(n);i++)
#define REP1(i,n) for(int i=1;i<(n);i++)
#define REP2(i,d,n) for(int i=(d);i<(n);i++)
#define RREP(i,n) for(int i=(n);i>=0;i--)
#define CLR(a)      memset((a),0,sizeof(a))
#define MCLR(a)     memset((a),-1,sizeof(a))
#define RANGE(x,y,maxX,maxY) (0 <= (x) && 0 <= (y) && (x) < (maxX) && (y) < (maxY))

using namespace std;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef vector<VI > VVI;
typedef vector<string> VS;
typedef vector<LL> VLL;
typedef pair<int,int> PII;

const int INF = 0x3f3f3f3f;
const LL INFL = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-9;

const int DX[]={1,0,-1,0},DY[]={0,-1,0,1};

bool dp[1000000];

const int MAX_N = 1000000;

vector<int> prime;
bool is_prime[MAX_N+1];

// n以下の素数を生成する
void create_prime(int n){
	// 初期化
	is_prime[0] = is_prime[1] = false;
	for(int i=2;i<=n;i++){
		is_prime[i] = true;
	}
	
	for(int i=2;i<=n;i++){
		if(is_prime[i]){
			prime.push_back(i);
			for(int j=2*i;j<=n;j+=i){
				is_prime[j] = false;
			}
		}
	}
}

int main(){
	int n,x;
	create_prime(MAX_N);
	while(true){
		cin >> n >> x;
		if(n==0 && x==0) break;
		REP(i,x+1){
			dp[i] = false;
		}
		VI data;
		int buf;
		REP(i, n){
			cin >> buf;
			data.PB(buf);
		}

		dp[0] = true;
		REP(i,x){
			if(dp[i]){
				REP(j, n){
					dp[i+data[j]] = true;
				}
			}
		}

		int ans = 0;
		REP(i, prime.size()){
			if(x <= prime[i]) break;
			if(dp[prime[i]]){
				ans = prime[i];
			}
		}

		if(ans != 0){
			cout << ans << endl;
		}else{
			cout << "NA" << endl;
		}
	}
}

C++: #include<iostream>
using namespace std;
const int INF = (1<<25);

bool dp[1000001];
int price[31];
int n, x;

int checkprime(int num) {
  for(int i=2; i*i<=num; i++) {
    if( num%i == 0 ) return true;
  }
  return x == 1;
}

int main() {
  while( cin >> n >> x, n || x ) {
    for(int i=0; i<n; i++) {
      cin >> price[i];
    }

    dp[0] = true;
    for(int i=1; i<=x; i++) {
      dp[i] = false;
    }

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

    int ans = INF;
    for(int i = x-1; i>1; i--) {
      if( dp[i] && !checkprime(i) ) {
	ans = i;
	break;
      }
    }

    cout << ans << endl;
  }
}

C++: #include <vector>
#include <iostream>
#include <utility>
#include <algorithm>
#include <string>
#include <deque>
#include <queue>
#include <tuple>
#include <queue>
#include <functional>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <complex>
#include <iterator>
#include <array>
#include <memory>
#include <stack>
#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 loop(i,s,n) for(int i=s;i<n;i++)
#define all(in) in.begin(), in.end()
template<class T, class S> void cmin(T &a, const S &b) { if (a > b)a = b; }
template<class T, class S> void cmax(T &a, const S &b) { if (a < b)a = b; }
#define MAX 1000000+1
using namespace std;
typedef pair<int, int> pii;
typedef pair<double,double>pdd;
typedef pair<ll,ll>pll;
int main(){
    int n;
    vector<bool>Isprime(MAX+1,true);
    vector<int>Prime(MAX+1,0); //Primearray
    int Primecounter =0;                  //Primearray counter;
    for(int i = 2; i<MAX+1;i++){
        if(Isprime[i]){
            for(int j = 2;i*j<MAX;j++)
                Isprime[i*j] = false;//テァツエツ?ヲツ閉ーテ」ツ?ェテ」ツつ臼rimearrayテ」ツ?ォテヲツ?シテァツエツ催」ツ?療」ツ?ヲテ」ツ?敕」ツ?ョテ・ツ?催ヲツ閉ーテ」ツつ津・ツ?ィテ」ツ?ヲfalseテ」ツ?ォ
            Prime[Primecounter] = i;
            Primecounter++;
        }
    }
    int x;
    while(cin>>n>>x,n+x){
        vvi dp(1000000+1,vi(30,0));
        vi tiya;
        rep(i,n){
            int gotiusa_is_a_god_anime;
            cin>>gotiusa_is_a_god_anime;
            tiya.push_back(gotiusa_is_a_god_anime);
            dp[gotiusa_is_a_god_anime][i]=1;
        }
        rep(i,x+1)rep(j,n){
            if(dp[i][j]){
                dp[i][j+1]=dp[i][j];
               if(i+tiya[j]<=x) dp[i+tiya[j]][j]=1;
            }
        }
        int maxi=-INF;
        for(int i=1; i<=x;i++)if(Isprime[i]&&dp[i][n])cmax(maxi,i);
        if(maxi!=-INF&&maxi!=1)cout<<maxi<<endl;
        else cout<<"NA"<<endl;
    }
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <cctype>

#include <iostream>
#include <vector>
#include <deque>
#include <queue>
#include <map>
#include <algorithm>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)
#define repi(i,l,n) for(int (i)=(int)(l);(i)<(int)(n);(i)++)
#define d_arr(arr, h, w) rep(i,(h) ){ cout << "["; rep(j,(w) ) { cout << (arr)[i][j] << ", "; } cout << "]" << endl;}
#define IN(x,s,g) ((x) >= (s) && (x) < (g))
#define ISIN(x,y,w,h) (IN((x),0,(w)) && IN((y),0,(h)))
#define print(x) printf("%d\n",x);

typedef pair<int ,int> P;

#define max_m 1000001
//prime table : if index is prime then return true
bool prime[max_m];
//if index can be made , return true:
bool dp[max_m];

void sieve(){
    rep(i,max_m){
        prime[i] = true;
    }
    prime[0] = false;
    prime[1] = false;
    repi(i,2,max_m){
        for(int j=2*i;j<max_m;j+=i){
            prime[j] = false;
        }
    }
}


int main()
{
    sieve();
    while(1){
        int n,x;
        cin >> n >> x;
        if( n == 0 && x == 0 ) { break; }
        int dish[n];
        rep(i,max_m){ dp[i] = false; }
        rep(i,n){
            cin >> dish[i];
            dp[dish[i]] = true;
        }

        //puts(" dp initiated ");
        rep(i,n){
            rep(j,x){
                if( dp[j] && j+dish[i] < max_m){
                    //cout << j + dish[i] << "," << endl;;
                    dp[j + dish[i]] = true;
                    //cout << j + dish[i] << "," << endl;;
                }
            }
        }
        //puts(" dp finisehd ");

        bool isna=true;
        for(int i=x; 0<=i; i--){
            if( dp[i] && prime[i] ) { 
                cout << i << endl;
                isna = false;
                break;
            }
        }
        if(isna){ cout << "NA" << endl; }
        

    }
}