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<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>

#define sint(i) scanf("%d",&i);
#define sintt(i,j) scanf("%d%d",&i,&j);
#define sinttt(i,j,k) scanf("%d%d%d",&i,&j,&k);
#define rep(i,n) for(int i=0;i<n;i++)

using namespace std;

int n,m;
int sina[301];
char memo[1000002];
char sosu[1000002];
char roop[1000002];

char N(int val){
	if(val<0 || val>1000000){
		return 0;
	}
	
	if(val==0){
		return 1;
	}
	
	if(memo[val]!=-1){
		return memo[val];
	}
	
	for(roop[val]=0; roop[val]<n; ++roop[val]){
		if(N(val-sina[roop[val]])==1){
			return memo[val] = 1;
		}
	}
	
	return memo[val]=0;
}

int main(){
	sosu[0]=1;sosu[1]=1;
	for(int i=2;i<1000001;i++){
		if(sosu[i]==1){
			continue;
		}
		for(int j=i*2;j<1000001;j+=i){
			sosu[j]=1;
		}
	}
	
	while(1){
		sintt(n,m);
		if(n==0)break;
		rep(i,n){
			sint(sina[i]);
		}
		
		rep(i,1000001){
			memo[i]=-1;
		}
		
		int flg=1;
		int ans=0;
		
		
		for(int i=m;i>0;i--){
			if(sosu[i]!=0){
				continue;
			}
			
			if(N(i)==1){
				ans=i;
				flg=0;
				break;
			}
		}
		
		/*
		rep(i,m){
			if(memo[i]==0){
				printf("%d\n",i);
			}
		}*/
		
		if(flg==1){
			puts("NA");
		}else{
			printf("%d\n",ans);
		}
	}
}

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<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 rrep(s,i,n) for(int i=(s);i<(n);i++)
 
using namespace std;
 
typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;
 
const int INF=1<<29;
const double EPS=1e-9;
 
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};

int gold[1000001];
int n,x;

bool sosu(int x){
	if( x == 1 || x == 2 || x == 3){
		return true;
	}
	for(int i=2;i*i<=x;i++){
		if(x%i==0){
			return false;
		}
	}
	return true;
}

int main(){
	while(true){
		cin >> n >> x;
		if(n == 0){
			break;
		}
		memset(gold,0,sizeof(gold));

		vi meshi;
		int buf;
		rep(i,n){
			cin >> buf;
			meshi.pb(buf);
			gold[buf] = 1;
		}

		rep(i,x){
			if(gold[i] == 1){
				rep(j,meshi.size()){
					if(i+meshi[j] <= x){
						gold[i+meshi[j]] = 1;
					}
				}
			}
		}

		buf = x;
		while(true){
			if(x==0){
				break;
			}
			if(gold[x] == 1){
				bool check = sosu(x);
				if(check){
					break;
				}
			}

			
			x--;
		}
		if(x==0){
			cout << "NA" << endl;
		}else{
			cout << x << endl;
		}

		
	}
}

C++: #include<stdio.h>
#include<string.h>
int prime(int);
int p[1000001]={};
int main(){
	int n,x,v[30],i,j,o,a;
	while(1){
		memset(p,0,sizeof(p));
		memset(v,0,sizeof(v));
		scanf("%d %d",&n,&x);
		if(n==0&&x==0){
			break;
		}
		for(i=0;i<n;i++){
			scanf("%d",&v[i]);
			p[v[i]]=1;
		}
		for(i=0;i<=x;i++){
			if(p[i]){
				for(j=0;j<n;j++){
					if(i+v[j]<=x){
						p[i+v[j]]=1;
					}
				}
			}
		}
		o=0;
		for(i=x;i>=0;i--){
			if(p[i]){
				if(prime(i)){
					o=1;
					break;
				}
				
			}
		}
		if(o){
			printf("%d\n",i);
		}
		else{
			printf("NA\n");
		}
	}
	return 0;
}
int prime(int x){
	int i;
	if(x<2) return 0;
	else if(x==2) return 1;
	if(x%2==0) return 0;
	for(i=3;i*i<=x;i+=2){
		if(x%i==0) return 0;
	}
	return 1;
}

C++: #include <cstdio>
#include <cctype>
#include <utility>
#include <bitset>
#include <cmath>
#include <algorithm>
using namespace std;

const auto gcu = getchar_unlocked;
const auto pcu = putchar_unlocked;
#define _DEF(r, n, ...) inline r n(__VA_ARGS__) noexcept
#define _T template <typename T>
#define _HT template <typename H,typename... T>
_T _DEF(T,in,int c){T n=0;int m=1;while(isspace(c)){c=gcu();}if(c=='-')m=-1,c=gcu();
	do{n=10*n+(c-'0'),c=gcu();}while(c>='0'&&c<='9');return m*n;}
_DEF(int, in){return in<int>(gcu());}
#define _SCAN(...) _DEF(bool,scan,__VA_ARGS__)
_T _SCAN(T &n){int c=gcu();return c==EOF?false:(n=in<T>(c),true);}
_DEF(bool, scan, char &c){c=gcu();gcu();return c!=EOF;}
#ifdef _GLIBCXX_STRING
_SCAN(string &s){int c;s="";
	for(;;){c=gcu();if(c=='\n'||c==' ')return true;else if(c==EOF)return false;s+=c;}}
#endif
_HT _SCAN(H &h,T&&... t){return scan(h)&&scan(t...);}
#define _OUT(...) _DEF(void,out,__VA_ARGS__)
#define _OUTL(...) _DEF(void,outl,__VA_ARGS__)
_OUT(bool b){pcu('0'+b);}
_OUT(const char *s){while(*s)pcu(*s++);}
_OUT(char c){pcu(c);}
#ifdef _GLIBCXX_STRING
_OUT(string s){for(char c:s)pcu(c);}
#endif
_T _OUT(T n){static char b[20];char *p=b,m=n<0?pcu('-'),-1:1;
	if(!n)*p++='0';else while(n)*p++=n%10*m+'0',n/=10;while(p!=b)pcu(*--p);}
_OUTL(){out('\n');}
#ifdef _GLIBCXX_VECTOR
_T _OUT(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);outl();}
#endif
_HT _OUT(H&& h, T&&... t){out(h);out(move(t)...);}
template <typename... T> _OUTL(T&&... t){out(move(t)...);outl();}

template<int N>
struct sieve {
	bool s[N];
	sieve() : s() {
		s[2] = true;
		for (int i = 3; i < N; i += 2)
			s[i] = true;
		for (int i = 9; i < N; i += 6)
			s[i] = false;
		for (int i = 6, e = sqrt(N); i <= e; i += 6) {
			for (int j : {i - 1, i + 1})
				if (s[j])
					for (int k = j * j; k < N; k += j)
						s[k] = false;
		}
	}
};

int main() {
	sieve<1000001> s;
	bitset<1000001> dp;
	for (int n, x; n = in(), x = in();) {
		dp = 1;
		while (n--)
			for (int i = in(); i <= x; i <<= 1)
				dp |= dp << i;
		int r = [&] {
		for (int i = x; i > 1; i--)
			if (dp[i] && s.s[i])
				return i;
		return 0;}();
		if (r)
			outl(r);
		else
			outl("NA");
	}
}