Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var sc = bufio.NewScanner(os.Stdin)

//Sliceconvtoi ...
func Sliceconvtoi() []int {
	strs := strings.Split(sc.Text(), " ")

	var ints []int
	var x int

	for _, s := range strs {
		x, _ = strconv.Atoi(s)
		ints = append(ints, x)
	}

	return ints
}

func isLeapYear(y int) bool {
	return (y%4 == 0 && y%100 > 0) || (y%4 == 0 && y%400 == 0)
}

func cntLeap(y []int) {
	cnt := 0

	for i := y[0]; i <= y[1]; i++ {
		if isLeapYear(i) {
			cnt++
			fmt.Println(i)
		}
	}

	if cnt == 0 {
		fmt.Println("NA")
	}
}

func main() {
	num := 0

	for sc.Scan() {
		y := Sliceconvtoi()

		if y[0] == 0 && y[1] == 0 {
			break
		}

		if num > 0 {
			fmt.Println()
		}

		cntLeap(y)
		num++
	}

}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>

using namespace std;

#define FOR(i,a,b) for(long long i=(a);i<(b);i++)
#define REP(i,N) for(long long i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define fi first
#define se second

#define PI acos(-1.0)
#define INF 1000000007

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<double, double> PD;
typedef pair<string, ll> PS;
typedef vector<ll> V;

int a, b;
V vi;
bool f = 0;
int main(){
	while (cin >> a >> b&&a+b){
		if (f)cout << "" << endl;
		f = 1;
		for (int i = a; i <= b; i++){
			if (i % 4 == 0){
				if (i % 100 == 0){
					if (i % 400 == 0){
						vi.push_back(i);
					}
					continue;
				}
				vi.push_back(i);
			}
		}
		if (vi.empty())cout << "NA" << endl;
		REP(i, vi.size()){
			cout << vi[i] << endl;
		}
		vi.clear();
	}
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<cstdio>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<map>
#include<functional>
using namespace std;
int stoi(string x){stringstream ss;ss<<x;int tmp;ss>>tmp;return tmp;}
string itos(int x){stringstream ss;ss<<x;return ss.str();}


int main(){
	int a,b;
	while(cin>>a>>b,a!=0||b!=0){
	bool f=1;
	for(int i=a;i<=b;i++){
	if(i%4==0&&a%4!=0||i%400==0){cout<<i<<endl;f=0;}
	}
	if(f)cout<<"NA\n";
	cout<<endl;
	}
	return 0;
}

C++: #include<stdio.h>
/*与えられた期間の間のうるう年をすべて出力*/
void leap_year(int year1, int year2);

int main(void)
{
    while(1){
        int a, b; /*a は year1　, b は year2*/
        scanf("%d %d", &a, &b);
        if (a == 0 && b == 0){
            break;
        }else if (a == b){
            printf("NA\n");
            printf("\n");
        }else {
            leap_year(a, b);
        }
    }
    return 0;
}

void leap_year(int year1, int year2)
{   
    int limit; /*もしも、うるう年がなかった時に使う*/
    for(int i = year1; i <= year2; ++i){
        if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0){
            printf("%d\n", i);
        }else{
            ++limit;
        }
    }
    if (limit == (year2 - year1 + 1)){/*うるう年がない場合*/
        printf("NA\n");
        printf("\n");
    }else{    /*うるう年がある場合*/
    printf("\n");
    }
}

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

bool uruu[3000] = {};

void is_uruu(){
	for(int i = 0;i < 3000;i++){
		if(i % 4 == 0){
			if(i % 100 == 0){
				if(i % 400 == 0) uruu[i] = true;
				else uruu[i] = false;
			}
			else uruu[i] = true;
		}
	}
}

int main(){
	int a,b;
	is_uruu();
	bool start = false;
	while(cin >> a >> b,a){
		if(!start) start = true;
		else cout << endl;
		bool flag = false;
		for(int i = a;i <= b;i++){
			if(uruu[i]){
				flag = true;
				cout << i << endl;
			}
		}
		if(!flag) cout << "NA" << endl;
	}
	return 0;
}

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

using namespace std;

int main(){
  int i, a, b, leap;
  vector<int> leapyear;

  while(1){
    cin >> a >> b;
    if(a == 0 && b == 0) break;

    for(i=a; i<=b; ++i){
      if(i%400 == 0)
	leap = 1;
      else if(i%100 == 0)
	leap = 0;
      else if(i%4 == 0)
	leap = 1;
      else
	leap = 0;

      if(leap == 1)
	leapyear.push_back(i);
    }

    if(leapyear.size() == 0){
      cout << "NA" << endl;
    }else{
      for(vector<int>::size_type i=0; i != leapyear.size(); ++i)
	cout << leapyear[i] << endl;
    }
    cout << endl;
    leapyear.clear();
  }

  return 0;
}

C++: #include <iostream>

int leap_year(int year)
{
	if ( year % 4 == 0) {
		if ( year % 100 == 0) {
			if ( year % 400 == 0) {
				return 1;
			} else {
				return 0;
			}
		} else {
			return 1;
		}
	} else {
		return 0;
	}
}

int main()
{
	int a, b;
	
	while (true) {
		std::cin >> a >> b;
		if (a == 0 && b == 0) {
			break;
		} else {
			int i = 0;
			for (int j = 0; a + j <= b; j++) {
				if (leap_year(a + j) == 0) {
					i++;
				} else {
					std::cout << a + j << std::endl;
				}
			}
			if ( i == a - b + 1) {
				std::cout << "NA" << std::endl;
			}
			
			std::cout << std::endl;
		}
	}
	
	return 0;
}

C++: #include <iostream>
#include <stdio.h>

bool judge(int year);
#include <iostream>
#include <stdio.h>

bool judge(int year);

int main() 
{
	int a, b;
	
	while (true) {
		int check = 0;
		std::cin >> a >> b;
		
		if (a == 0 && b == 0) {
			break;
		}
		
		for (int i = a; i <= b; i++) {
			if (judge(i)) {
				std::cout << i << std::endl;
				check = 1;
			}
		}
		
		if (check == 0) {
			std::cout << "NA" << std::endl;
		}
		
		std::cout << std::endl;
	}
	return 0;
}


bool judge(int year){
	if ((year % 4 == 0 && !(year % 100 == 0)) || year % 400 == 0) {
		return true;
	} else {
		return false;
	}
}

C++: 
#include<iostream>
#include<string>
#include<cmath>
#include<vector>
#include<stack>
#include<queue>
#include<algorithm>
#include<complex>
using namespace std ;
typedef vector<int> vi ;
typedef vector<vi> vvi ;
typedef vector<string> vs ;
typedef pair<int, int> pii; 
typedef long long ll ;

#define loop(i,a,b) for(int i = a ; i < b ; i ++)
#define rep(i,a) loop(i,0,a)
#define all(a) (a).begin(),(a).end()

int main(void){
  int b,e;
  while(cin >> b >> e , b+e){
    bool na=false;
    loop(i,b,e){
      if(i % 4 == 0){
	if(i % 100 == 0){
	  if(i % 400 == 0){
	    cout << i << endl;
	    continue;
	    na = true;
	  }
	  continue;
 	}
	cout << i << endl;
	na = true;
      }
    }
    if(!na)cout << "NA" << endl;
    cout << endl;
  }

}

C++: #include <stdio.h>
#include <stdbool.h>
 
bool is_leap_year(int y);
int  get_leap_years(int list[], int begin, int end);
 
int main(void)
{
    int leap_years_list[1000]; //A.D. 0 - A.D. 3000 の間に閏年は高々1000個しかない
 
    bool first_set = true; //一つ目のセットの前にだけは改行を入れてはいけないので
 
    while (true) {
        int year_begin, year_end;
 
        //読み込み
        scanf("%d %d", &year_begin, &year_end);
 
        //終了判定
        if (year_begin == 0 && year_end == 0) {
            break;
        }
 
        //閏年を計算する
        int leap_years_count = get_leap_years(leap_years_list, year_begin, year_end);
 
        //セットとセットの間には空行を入れる
        if (first_set) {
            first_set = false;
        } else {
            putchar('\n'); //putcharは一文字だけ出力する関数です
        }
 
        //閏年を出力
        if (leap_years_count == 0) {
            puts("NA"); //putsは与えられた文字列を出力した後改行する関数です
        } else {
            for (int i = 0; i < leap_years_count; i++) {
                printf("%d\n", leap_years_list[i]);
            }
        }
 
    }
}

int  get_leap_years(int list[], int begin, int end)
{
    int i;
    for (int year = begin; year <= end; year++) {
    if (is_leap_year(year)) {
    list[i] = year
    i++;
    }
    }
    return i;
}

bool is_leap_year(int y)
{
    if (y % 400 == 0) {
        return true;
    } else if (y % 100 == 0) {
        return false;
    } else {
        return y % 4 == 0;
    }
}