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 <set>
#include <map>
#include <list>
#include <queue>
#include <stack>
#include <cmath>
#include <ctype.h>
#include <ctime>
#include <cstdio>
#include <vector>
#include <string>
#include <bitset>
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <numeric>
#include <complex>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <cassert>
#include <iostream>
#include <iterator>
#include <algorithm>

using namespace std;

#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i, n) REP(i, 0, n)
#define lengthof(x) (sizeof(x) / sizeof(*(x)))
#define FILL(ptr, value) FILL_((ptr), sizeof(ptr)/sizeof(value), (value))
template <typename T>
void FILL_(void * ptr, size_t size, T value){
  std::fill((T*)ptr, (T*)ptr+size, value);
}
//4方向ベクトル→↑←↓
int dx[] ={1,0,-1,0};
int dy[] ={0,-1,0,1};
int n;//料理の種類
int x;
int sum;
bool prime[1000001];
int main()
{

  for(int i = 0;i <1000001;i++){
    prime[i] = true;
  }
  prime[0] = false;
  prime[1] = false;
  for(int i = 2;i <1000001;i++){
    if(prime[i]){
      for(int j = 2*i;j <1000001;j+=i){
	prime[j]= false;
      }
    }
  }
  while(cin>>n>>x,n||x){
    bool flag1=false;
    int dish[40];
    bool check[1000001];
    for(int i = 0;i < 1000001;i++){
      check[i]=false;
    }
    for(int i = 0;i < n;i++){
      cin>>dish[i];
    }
    check[0] =true;//0はどの料理からでも作れる
    for(int i = 0;i <=x;i++){
      if(check[i]){
	for(int j = 0;j <n;j++){
	  if(i + dish[j]<=x)
	    check[i+dish[j]] = true;
	}
      }
    }
    int ans = 0;

    for(int i =x;i >0;i--){//上から調べる
      if(check[i]&&prime[i]){
	flag1 = true;
	ans = i;
	break;
      }
    }
 for(int i = 0 ;i < 10000000000;i++){
     x +=1;
     x -=1;
}
    if(flag1)
      cout <<ans<<endl;
    else
      cout <<"NA"<<endl;
  }

  return 0;
}

C++: #include<iostream>
#include<algorithm>
#define INF 999999
typedef long long ll;
using namespace std;
int n,a,b,c,maxm,x;
int sum,miniNo,minim;
bool t[1000001];
bool isPrime(int x){
	for(int i=2;i*i<=x;i++){
		if(x%i==0)return false;
	}
	return true;
}
int main(){
	while(1){
		fill(t,t+1000001,0);
		cin>>n>>x;
		if(n==0)break;
		for(int i=0;i<n;i++){
			cin>>a;
			t[a]=true;
			for(int j=1;j+a<1000001;j++){
				t[j+a]=(t[j]||t[j+a]);
			}
		}
		b=0;
		for(int i=x;i>=1;i--){
			if(isPrime(i)&&t[i]){
				cout<<i<<endl;
				b=1;
				break;
			}
		}
		if(b==0)cout<<"NA"<<endl;
	}
	return 0;
}

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

using namespace std;

int main()
{
	vector<int> prime;
	int i,j;
	
	for(i=0;i<1000001;i++)
		prime.push_back(1);
	
	prime[0]=prime[1]=0;
	
	for(i=2;i<1000001;i++)
	{
		if(prime[i]==1)
		{
			for(j=2;j*i<1000001;j++)
				prime[j*i]=0;
		}
	}
	
	int n,x,ans;
	
	for(;;)
	{
		cin >> n >> x ;
		if(n==0 && x==0)
			break;
		
		vector<int> price;
		ans=0;
		
		for(i=0;i<n;i++)
		{
			int a;
			cin >> a;
			price.push_back(a);
		}
		
		vector<int> sans;
		
		for(i=0;i<1000001;i++)
			sans.push_back(0);
		
		for(i=0;i<price.size();i++)
			sans[price[i]]=1;
		
		for(i=0;i<=x;i++)
		{
			if(sans[i]==1)
			{
				if(prime[i]==1)
					ans=i;
				for(j=0;j<price.size();j++)
				{
					if(i+price[j]<=x)
					{
						sans[i+price[j]]=1;
					}
				}
			}
		}
		
		if(ans==0)
			cout << "NA" << endl;
		else
			cout << ans << endl;
	}
}

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
/*void dfs(int num){
    if(flag) return;
    if(ans==num){flag=true;return;}
    if(num>ans){memo[num]=false;return;}
    else rep(i,n){
        cout<<num<<endl;
      if(num+v[i]<=ans&&memo[num+v[i]])dfs(num+v[i]);
    }
    memo[num]=false;
    return;
}*/
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++;
        }
    }
    int m,n,ans; bool flag;
    while(cin>>n>>m,n+m){
        vi v;
        int temp;
        flag=false;
        rep(i,n){cin>>temp; v.push_back(temp);}
        for(int i=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]<=MAX)array[i+v[j]]=true;
            if(array[ans])break;
        }
        if(array[ans]) cout<<ans<<endl;
        else 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;
      }
    }
  }
  return 0;
}