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>
using namespace std;
int prime[200];
bool ans[1000001];
int main(){
	int count=0;
	for(int i=2;i<1000;i++){
		bool t=true;
		for(int j=0;j<count;j++){
			if(i%prime[j]==0)
				t=false;
		}
		if(t==true){
			prime[count]=i;
			count++;
		}
	}
	int n,x,m;
	while(true){
	cin>>n>>x;
	if(n==0&&x==0)
		break;
	ans[0]=true;
	for(int i=1;i<x;i++)
		ans[i]=false;
	for(int u=0;u<n;u++){
		cin>>m;
		for(int i=0;i<m;i++){
			bool t=false;
			for(int j=i;j<=x;j+=m){
				if(ans[j]==true)
					t=true;
				if(t==true)
					ans[j]=true;
			}
		}
	}
	int best=x;
	while(true){
		if(ans[best]==true){
			bool t=true;
			for(int i=0;i<count;i++){
				if(best%prime[i]==0)
					t=false;
			}
			if(t==true)
				break;
		}
		best--;
		if(best==1)
			break;
	}
	if(best==1)
		cout<<"NA"<<endl;
	else
		cout<<best<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
using namespace std;

int main() {

	while(true)
	{
		int N,X;
		cin >> N >> X;
		if(N==0 && X==0)break;
		
		vector<int> food;
		for(int i=0;i<N;i++){
			int m;
			cin >> m;
			food.push_back(m);
		}
		
		vector<int> num(X+1);
		vector<int> prim(X+1);
		fill(num.begin(),num.end(),0);
		fill(prim.begin(),prim.end(),1);
		for(int i=0;i<N;i++){
			num[ food[i] ]=1;
		}
		for(int i=0;i<X+1;i++){
			if( num[i]!=0){
				for(int j=0;j<N;j++){
					if( i+food[j]>=num.size())break;
					num[i+food[j]]=1;
				}
			}
		}
		prim[0]=0;
		prim[1]=0;
		for(int i=2;i<X+1;i++){
			if( prim[i]!=0 ){
				int x=i+i;
				while(x<X+1){
					prim[x]=0;
					x+=i;
				}
			}
		}
		int ans=-1;
		for(int x=X;x>=0;x--){
			if( prim[x]==1 && num[x]!=0){
				ans = x;
				break;
			}			
		}
		if(ans>0){
			cout << ans << endl;
		}else{
			cout << "NA" << endl;
		}
	}
	


	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>

using namespace std;

int dp[1000001];
int kind[31];


const int MAX_SIZE = 10000;
const int MAX_PRIME = 1000000;


int prime[MAX_PRIME+1];
bool isPrime[MAX_PRIME+1];
int p;

void erats(){
	// primeXgðú»
	fill(isPrime,isPrime+MAX_PRIME,true);
	p = 0;
	isPrime[0] = isPrime[1] = false;

	for(int i = 2; i <= MAX_PRIME; i++){
		if(isPrime[i]){
			prime[p++] = i;
		}
		else
			continue;

		// Óé¢É©¯é
		for(int j = 2*i; j <= MAX_PRIME; j+=i){
			isPrime[j] = false;
		}
	}
}


int main(){

	int n;
	int x;
	erats();
	while(cin>>n>>x&&!(n==0&&x==0)){
		for(int i = 0; i < n; i++){
			cin>>kind[i];
		}
		// eàzÌ¥¢ûª½íÞ é©ðßé
		//fill(dp,dp+1000001,0);
		dp[0]=1;
		int maxCost=-1;

		//for(int j = 0; j < n; j++){
		//	for(int i = kind[j]; i <= x; i++){
		//		dp[i]+=dp[i-kind[j]];
		//	}
		//}

		for(int i = 1; i <= x; i++){
			dp[i]=0;
			for(int j = 0; j < n; j++){
				if(i-kind[j]>=0){
					dp[i]+=dp[i-kind[j]];
				}
			}
			if(dp[i]&&(isPrime[i]||i==1)){
				maxCost=i;
			}
		}
		//for(int i = 0; i <= x; i++){
		//	if(dp[i]&&isPrime[i])
		//		maxCost=i;
		//}


		if(maxCost==-1)
			cout<<"NA"<<endl;
		else
			cout<<maxCost<<endl;
	}

	return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <iostream>
#include <sstream>
#include <climits>
#include <cfloat>
#include <complex>

using namespace std;

bool isPrime[1000001];
bool dp[1000001];
int main()
{
	fill(isPrime, isPrime+1000001, true);
	isPrime[0] = isPrime[1] = false;
	for (int i = 2; i*i <= 1000000; ++i)
	{
		if (isPrime[i])
		{
			for (int j = 2*i; j <= 1000000; j += i)
				isPrime[j] = false;
		}
	}

	int n, x;
	while (scanf("%d %d", &n, &x), n | x)
	{
		int v[30];
		for (int i = 0; i < n; ++i)
		{
			int t;
			scanf("%d", &t);
			v[i] = t;
		}

		fill(dp, dp+x+1, false);
		dp[0] = true;
		for (int i = 0; i <= x; ++i)
			if (dp[i])
				for (int j = 0; j < n; ++j)
					if (i + v[j] <= x)
						dp[i + v[j]] = true;

		int ans;
		for (ans = x; ans > 0; --ans)
			if (dp[ans] && isPrime[ans])
				break;
		if (ans)
			printf("%d\n", ans);
		else
			puts("NA");
	}

	return 0;
}

C++: // AOJ 0202
#include<algorithm>
#include<iostream>
#include<cstring>

bool isprime[1000001], dp[1000001];

void sieve()
{
	std::fill( isprime, isprime + 1000000, true );
	isprime[0] = isprime[1] = false;

	for( int i = 2; i <= 1000000; ++i )
		if( isprime[i] )
			for( int j = i * 2; j <= 1000000; j += i )
				isprime[j] = false;

	return;
}

int main()
{
	int n, x;

	sieve();

	while( std::cin >> n >> x, n | x )
	{
		memset( dp, false, sizeof( dp ) );
		dp[0] = true;

		int ans = 0;
		for( int i = 0; i != n; ++i )
		{
			int p;
			std::cin >> p;

			for( int j = p; j <= x; ++j )
			{
				if( dp[j-p] )
				{
					dp[j] = true;
					if( isprime[j] )
						ans = std::max( ans, j );
				}
			}
		}

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

	return 0;
}

C++: #include<bits/stdc++.h>
#define int long long
#define for0(i, n) for(int i = 0; i < (n); i++)
#define for1(i, n) for(int i = 1; i <= (n);i++)
using namespace std;
int n, x;
bool b[1010000];
vector<int>prime;
signed main() {
	prime.push_back(2);
	for (int i = 3; i < 999999; i += 2) {
		bool b00l = 0;
		for (int p : prime) {
			if (i % p == 0) { b00l = 1; break; }
			if (p > sqrt(i))break;
		}
		if (!b00l)prime.push_back(i);
	}
	while (cin >> n >> x, n) {
		for1(i, x)b[i] = 0;
		b[0] = 1;
		for1(gr4cv, n) {
			int p; cin >> p;
			for0(i, x)if (i + p > x)break; else if (b[i])b[i + p] = 1;
		}
		int ans = -1;
		for (int p : prime)if (p > x)break; else if (b[p])ans = p;
		if (ans < 0)cout << "NA\n";
		else cout << ans << endl;
	}
}

C++: #include <stdio.h>

int n,m[30];
/*
bool prime[1000000];
*/
bool c[1000000];

void saiki(int total){
	int i;
	if(total<=0){
		return;
	}
	
	for( i=0 ; i<n ; i++){
		total-=m[i];
		if(c[total]==1)continue;
		if(total>=0){
			c[total]=1;
		}
		saiki(total);
	}
}

int check(int prime){
	int flg=0,i;
	if(prime%2==0)return 0;
	for(i=3;i<prime;i+=2){
		if(prime%i==0){
			flg=1;
		}
	}
	if(flg==1)return 0;
	return 1;
}

int main(void)
{
	int i,j;
	//f
	/*
	prime[0]=1;
	prime[1]=1;
	for(i=3;i<1000000;i++){
		if(i%2==0){
			prime[i]=1;
		}
	}
	for(i=3;i<1000000;i++){
		if(prime[i]==0){
			for(j=(i+i);j<1000000;j+=i){
				prime[j]=1;
			}
		}
	}
	*/
	//
	while(1){
		int x;
		int flg=0;
		scanf("%d%d",&n,&x);
		if(n==0)break;
		
		for(i=0;i<n;i++){
			scanf("%d",&m[i]);
		}
		saiki(x);
		//
		for(i=0;i<x;i++){
			
			if(c[i]==1 && check(x-i)){
				flg=1;
				break;
			}
		}
		if(flg==1){
			printf("%d\n",x-i);
		}
		else puts("NA");
		for(i=0;i<1000000;i++){
			c[i]=0;
		}
		//
	}
	
	
	return 0;
}