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 <stdio.h>
#include <stdbool.h>

bool is_leap_year(int y);

int get_leap_years(int* leap_year_array, int start_year, int final_year);
int main()
{
    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]);
            }
        }
        
    }
}

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

int get_leap_years(int* leap_year_array, int start_year, int final_year)
{
    int count = 0;
    for(int i = start_year; i <= final_year; i++){
        if(is_leap_year(i)){
            leap_year_array[count] = i;
            count++;
        }    
    }
    return count;
}

C++: #include <stdio.h>

int main(){

	int a,b;
	int i;
	int answer;
	int count;

	while(1){

		count = 0;

		scanf("%d %d",&a,&b);

		if(a == 0 && b == 0){
			break;
		}

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

	return 0;
}

C++: #include <stdio.h>

void judge_leap_year(int a, int b);

int existance_leap_year(int a, int b);

int main(void)
{
    while(1) {
      int exist;
      int start_year, end_year;
      scanf("%d %d", &start_year, &end_year);
      if (start_year == 0 && end_year == 0) {
        break;
      } else {exist = existance_leap_year(start_year, end_year);
        if (exist == 1) {
          printf("\n");
          judge_leap_year(start_year, end_year);
        } else {
          printf("NA\n");
        }
      }
    }
    return 0;
}

void judge_leap_year(int a, int b)
{
    int year;
    for (year = a; year <= b; year++) {
      if (year % 400 == 0) {
        printf("%d\n", year);
      } else if (year % 4 == 0 && year % 100 != 0) {
        printf("%d\n", year);
      }
    }
}
//閏年を記述する                                                                                                                                                                     

int existance_leap_year(int a, int b)
{
    int n = 0;
    int year;
    for (year = a; year <= b; year++) {
      if (year % 400 == 0) {
        n = 1;
        break;
      } else if (year % 4 == 0 && year % 100 != 0) {
        n = 1;
        break;//一度閏年を検出した時点でループを抜ける。                                                                                                                             
      }
    }
    return n;
}
//閏年があった時、１を返す

C++: #include <iostream>

int LeapYear (int x);
int main()
{
    int a,b;
    std::cin >> a >> b;
    while (true) {
        int n = 0;
        if (a == 0 && b == 0) {
	        break;
        } else {
            for (int i = a; i <= b; i++) {
                if (LeapYear (i) == 1) {
                    std::cout << i <<std::endl;
                    n++; //kokode "n" ni kasan sareru to sita de NA ga denakunaru
            }				
        }
        if (n == 0) {
            std::cout << "NA" << std::endl;
        }
        std::cin >> a >> b;
        }
    }
    return 0;
}

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

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

int p[3000];

void leap(){
	fill(p, p+3000, false);
	for(int i=1; i < 3000; i++){
		if(i % 400 == 0) p[i] = true;
		else if(i % 100 == 0) continue;
		else if(i % 4 == 0) p[i] = true;
	}
}

int main(){
	leap();
	int a, b;
	bool hoge = false;
	while(cin >> a >> b, a || b){
		bool empty = false;
		if(!hoge) hoge = true;
		else cout << endl;

		for(int i=a; i <= b; i++){
			if(p[i]){
				cout << i << endl;
				empty = true;
			}
		}
		if(!empty) cout << "NA" << endl;
	}
}

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

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

using namespace std;

int main(){
	
	int a, b;
	
	bool first;
	
	cin >> a >> b;
	
	while(a != 0 && b != 0){
		
		first = false;
		
		for(int i = a; i <= b; i++){
			if(i % 4 == 0){
				if(i % 100 == 0){
					if(i % 400 == 0){
						printf("%d\n", i);
						first = true;
						continue;
					}
					continue;
				}
				printf("%d\n", i);
				first = true;
				continue;
			}
		}
		
		if(!first){
			printf("NA\n");
		}
		
		printf("\n");
		
		cin >> a >> b;
	}
	
	return 0;
}

C++: #include<stdio.h>
 
int main(){
	int a, b, i;
	while(scanf("%d %d", &a, &b) != 0){
		if(a == 0 || b == 0) break;
		for(i = a; i <= b; i++){
			if(i % 400 == 0) printf("%d\n", i);
			else if(i % 100 == 0) printf("NA\n");
			else if(i % 4 == 0) printf("%d\n", i);
			else printf("NA\n");
		}
	}
	return 0;
}

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

bool leap(int x) {
	int flg=0;
	if (x % 4 == 0) { flg = 1; }
	if (x % 100 == 0) { flg = 0; }
	if (x % 400 == 0) { flg = 1; }

	return flg;
}

int main() {
	int a, b;
	vector<int>va;
	while (cin >> a >> b&&a!=0&b!=0) {
		for (int i = a; i <=b; i++) {
			int c = leap(i);
			if (c==1) { va.push_back(i); }
		}
		if (!va.empty()) {
			for (int i = 0; i < va.size(); i++) {
				cout << va[i] << endl;
			}
			cout << endl;
		}
		else { cout << "NA" << endl << endl; }
		va.erase(va.begin(), va.end());
	}
	return 0;
}