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;
void uruu(int, bool&);

int main() {
	int a, b;

	while (true) {
		cin >> a >> b;
		if (a == 0 && b == 0) break;
		bool flag = true;

		for (int i = a;i <= b;i++) {
			uruu(i, flag);
		}
		if (flag)cout << "NA" << endl;

		cout << endl;
	}

	return 0;
}

void uruu(int year, bool& flag) {
	if (year % 400 == 0) {
		cout << year << endl;
		flag = false;
		return;
	}
	else if (year % 100 == 0) {
		return;
	}
	else if (year % 4 == 0) {
		cout << year << endl;
		flag = false;
		return;
	}
	else {
		return;
	}
}

C++: #include <stdio.h>

int main(void)
{
    int a, b, count;
    while (1) {
        count = 0;
        scanf("%d %d", &a, &b);
        if ((a == 0) && (b == 0)) {
            break;
        } else {
            for (int i = a; i <= b; ++i) {
                if ((i % 4) == 0 && (!(i % 100) == 0 || (i % 400) == 0)) {
                    printf("%d\n", i);
                    ++count;
                }
            }
            if (count == 0) {
                printf("NA\n");
            }
        }
    }
        return 0;
}

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

int main() {
	int a, b;
	while (cin >> a >> b) {
		if ((a&b) == 0) break;
		int count = 0;
		for (int i = a; i <= b; i++) {
			if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0) {
				cout << i << "\n";
				count++;
			}
		}
		if (count == 0) cout << "NA\n\n";
		else cout << "\n";
	}
}

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);
    while (1) {
        if (first_year == 0 && last_year == 0) {
            break;
        } else {
            leap_year(first_year, last_year);
        }
        scanf("%d %d", &first_year, &last_year);
        }
    return 0;
}

int leap_year(int first_year, int last_year)
{
    int count = 0;
    printf("\n");
    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");
    }
}

C++: #include <iostream>
using namespace std;
void uruu(int, bool&);

int main() {
	int a, b;

	while (true) {
		cin >> a >> b;
		if (a == 0 && b == 0) break;
		bool flag = true;

		for (int i = a;i <= b;i++) {
			uruu(i, flag);
		}
		if (flag)cout << "NA" << endl;
		cout << endl;
	}

	return 0;
}

void uruu(int year, bool& flag) {
	if (year % 400 == 0) {
		cout << year << endl;
		flag = false;
		return;
	}
	else if (year % 100 == 0) {
		return;
	}
	else if (year % 4 == 0) {
		cout << year << endl;
		flag = false;
		return;
	}
	else {
		return;
	}
}

C++: #include <iostream>

using namespace std;

int main()
{
    while(1){
        int a,b,count=0;
        cin>>a>>b;if(a==0&&b==0)return 0;
        for(;a<=b;++a){
            if(a%4==0){
                if(a%100==0){
                    if(a%400==0){
                        cout<<a<<endl;++count;continue;
                        }
                        continue;
                }
                cout<<a<<endl;++count;
            }
        }
        if(count==0)cout<<"NA"<<endl;
        cout<<endl;
    }
}

C++: #include <iostream>
using namespace std;
int main()
{
    while(1){
        int a,b,count=0;
        do{cin>>a>>b;}while(a>=3000&&b>=3000);
        if(a==0&&b==0)return 0;
        for(;a<=b;++a){
            if(a%4==0){
                if(a%100==0){
                    if(a%400==0){
                        cout<<a<<endl;++count;continue;
                        }
                        continue;
                }
                cout<<a<<endl;++count;
            }
        }
        if(count==0)cout<<"NA"<<endl;
        cout<<'\n';
    }
}

C++: #include<cstdio>
#include<iostream>
#include<utility>

#define NMAX 1000000

using namespace std;

int main(void){

	int a,b;
	bool f;

	while(1){
		cin>>a>>b;
		if(a==0&&b==0) break;
		f=false;
		for(int i=a;i<=b;i++){
			if(i%4==0){
				if(i%100!=0||i%400==0){
					cout<<i<<endl;
					f=true;
				}
			}
		}
		if(!f) cout<<"NA"<<endl;
		cout<<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 j = 0;
    for (int year = begin; year <= end; year++) {
    if (is_leap_year(year)) {
    list[j] = year;
    j++;
    }
    }
    return j;
}

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 main(){
	int a, b, i, count = 0, s = 0;
	while(scanf("%d %d", &a, &b) != 0){
		if(a == 0 || b == 0) break;
		if(s == 1) printf("\n");
		for(i = a; i <= b; i++){
			if(i % 400 == 0){
				printf("%d\n", i);
				count = 1;
			}else if(i % 100 == 0) continue;
			else if(i % 4 == 0){
				printf("%d\n", i);
				count = 1;
			}
		}
		if(count == 0) printf("NA\n");
		count = 0;
		s = 1;
	}
	return 0;
}