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>
using namespace std;

int y[3001];

int main()
{
  for (int i = 4; i <= 3000; i += 4){
    y[i] = 1;
  }
  for (int i = 100; i <= 3000; i += 100){
    y[i] = 0;
  }
  for (int i = 400; i <= 3000; i += 400){
    y[i] = 1;
  }
  
  int a, b;
  cin >> a >> b;
  if (a == 0){
    return 0;
  }
  int c = 0;
  for (int i = a; i <= b; i++){
    if (y[i] == 1){
      cout << i << endl;
      c = 1;
    }
  }

  while (1){
    cin >> a >> b;
    if (a == 0){
      break;
    }
    c = 0;
    cout << endl;
    for (int i = a; i <= b; i++){
      if (y[i] == 1){
        cout << i << endl;
        c = 1;
      }
    }
    if (c == 0){
      cout << "NA" << endl;
    }
  }
  
  return 0;
}

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)) {
    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;
    }
}

C++: #include <stdio.h>

int leap_year(int, int);

int main(void)
{
	int a, b;
	while (1) {
		scanf("%d %d", &a, &b);
		if (a == 0 && b == 0) 
			break;
		leap_year(a, b);
	}
	return 0;
}

int leap_year(int a, int b)
{
	int leap_year_number = 0;
	for (int i = a; i <= b; i++) {
		if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0) {
			printf("%d\n", i);
			leap_year_number += 1;
		}
	}
	if (leap_year_number == 0) {
		printf("NA\n");
	}
	return 0;
}

C++: #include<iostream>

using namespace std;

int main() {
	int a[3000], b[3000],n=0;
	while(1){
		cin >> a[n] >> b[n];
	if (a[n] == 0 && b[n] == 0)break;
		n++;
	}
	for(int j=0;j<=n;j++){
		if (a[j] == 0 && b[j] == 0)break;
		int cnt = 0;
		for (int i = a[j]; i <= b[j]; i++) {
			
			if (i % 4 == 0) {
				if (i % 100 == 0) {
					if (i % 400 == 0) {
						cnt++;
						cout << i << endl;
					}
				}
				else {
					cnt++;
					cout << i << endl;
				}
			}
			if (i == b[j]) {
				if (cnt == 0)cout << "NA" << endl;
				cout << endl;
			}
		}
	}
	return 0;
}

C++: #include <stdio.h>

void uruu(int a, int b);

int main(void)
{
    int a;
    int b;
    scanf("%d %d", &a, &b);
    while (a != 0 || b != 0) {
        uruu(a, b);
        printf("\n");
        scanf("%d %d", &a, &b);
    }
    return 0;
}


void uruu(int a, int b)
{
    int count = 0;
    for (int year = a; year <= b; ++year) {
        if (year % 4 == 0) {
            if (year % 100 != 0) {
                printf("%d\n", year);
                ++count;
            } else {
                if (year % 400 == 0) {
                    printf("%d\n", year);
                    ++count;
                }
            }
        }   
    }
    if (count == 0) {
        printf("NA\n");
    }
}

C++: #include <iostream>
#include <math.h>
#include <stdio.h>
#include <string>
#include <string.h>
#include <algorithm>
#include <cmath>
#include <limits>
#include <sstream>
#include <iomanip>

using namespace std;

int main (void)
{
	for (int u = 0; u < 50; u++)
	{
		long n,m;
		cin >> n >> m;
		if (n == 0 && m == 0)
		{
			break;
		}
		int p = 0;

		for (int i = n; i < m + 1; i++)
		{
			if (i % 4 == 0 && i % 100 != 0)
			{
				p += 1;
				cout << i << endl;
			}
			else if (i % 400 == 0 && i % 100 != 0)
			{
				p += 1;
				cout << i << endl;
			}
			else if (i == m && p == 0)
			{
				cout << "NA" << endl;
			}
		}
		cout << endl;
	}
}

C++: #include<iostream>
using namespace std;
int main() {
	int a, b,ans;
	while (1) {
		cin >> a >> b;
		ans = 0;
		if (a == 0 && b == 0) {
			goto a;
		}
		for (int i = a; i <= b; i++) {
			if (i % 4 == 0) {
				if (i % 100==0) {
					if (i % 400==0) {
						cout << i << endl;
						ans = ans + 1;
					}
				}
				else {
					cout << i << endl;
					ans = ans + 1;
				}
			}
		}
		if (ans == 0) {
			cout << "NA" << endl;
		}
		cout << endl;
	}
a:;
}

C++: #include <stdio.h>

int leap_year(int first_year, int last_year);

int main(void)
{
    int first_year, last_year;
    scanf("%d %d", &first_year, &last_year);
    if (first_year != 0 && last_year != 0) {
        leap_year(first_year, last_year);
    }
    return 0;
}

int leap_year(int first_year,int last_year)
{
    static int count = 0;
    for (int year = first_year; year <= last_year; ++year) {
        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
           printf("%d\n", year);
        } else {
            ++count;
        }
    }
    if (count == last_year - first_year + 1) {
        printf("NA\n");
    }
    printf("\n");
}

C++: #include <stdio.h>
	
void uruu(int first, int end)
{
	int count = 0;
	for (int i = first; i < end + 1; i++) {	
		if (i % 400 == 0) {
			printf("%d\n", i);
			count = count + 1;
		} else if (i % 100 == 0) {
			i = i + 3;
		} else if (i % 4 == 0) {
			printf("%d\n", i);
			count = count + 1;
		}
	}
	if (count == 0) {
		printf("NA\n");
	}
}
	
int main(void)
{	
	int first, end, dataset;
	dataset = 0;
	while (1) {
		if (dataset != 0) {
		printf("\n");
		}
		scanf("%d %d", &first, &end);
		if (first == 0 && end == 0) {
			break;
		} else {
			uruu(first, end);
			dataset = dataset++;
		}
	}
	return 0;
}