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>
	
void uruu(int first, int end)
{
	int dataset;
	if (dataset != 0) {
		printf("\n");
	}
	dataset = 0;
	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");
	}
	dataset = dataset++;
}
	
int main(void)
{	
	int first, end;
	while (1) {
		scanf("%d %d", &first, &end);
		if (first == 0 && end == 0) {
			break;
		} else {
			uruu(first, end);
		}
	}
	return 0;
}

C++: #include <iostream>

using std::cout;
using std::endl;

bool isLeapYear(int year);

int main()
{
    int start, end;
    while (true) {
        std::cin >> start >> end;

        if (start == 0 && end == 0) {
            break;
        }

        static bool first_output = true;
        if (!first_output) {
            cout << endl;
        }
        first_output = false;

        int cnt = 0;
        for (int year = start; year <= end; year++) {
            if (isLeapYear(year)) {
                cout << year << endl;
                cnt++;
            }
        }
        if (cnt == 0) {
            cout << "NA" << endl;
        }
    }

    return 0;
}

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

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

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

C++: #include <stdio.h>

int count_number(void);

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

C++: #include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <sstream>
#include <vector>
#include <string>
#include <iomanip>
#include <bitset>
using namespace std;
#define INF	100000000
#define MOD 1000000007
#define pb push_back
#define mp make_pair
#define fi first
#define sec second
#define lb lower_bound
#define ub upper_bound
#define SS stringstream
#define rep(i,n) for(int i = 0; i < n; i++)
#define sz(x) ((int)(x).size())
#define SORT(x) sort((x).begin(), (x).end())
#define RSORT(x) sort((x).begin(), (x).end(), greater<int>() )
#define clr(a,b) memset((a),(b),sizeof(a))
typedef long long int ll;
typedef pair<int, int> P;
typedef vector<int> Vi;
typedef vector<ll> Vll;
typedef vector<P> Vp;
typedef priority_queue<P, vector<P>, greater<P> > PQ;

int a,b,t=0;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	while(cin >> a >> b){
		if(a == 0 && b == 0) break;
		if(t != 0) cout << endl;
		bool ok = true;
		for(int i = a; i <= b; i++){
			if(i%400==0||(i%100!=0&&i%4==0)){
				ok = false;
				cout << i << endl;
			}
		}
		if(ok) cout << "NA" << endl;
		t++;
	}
}

C++: #include <stdio.h>

bool isLeapYear(int year)
{
    if (year % 4 == 0) {
        if (year % 100 == 0) {
            if (year % 400 == 0) {
                return true;
            }
            return false;
        }
        return true;
    }
    return false;
}
        

int main(void)
{
    int year, from, until, num_leap_year;
    while (1) {
        num_leap_year = 0;
        scanf("%d %d", &from, &until);
        if (from == 0 && until == 0) {
            break;
        }
        for (year = from; year <= until; year++) {
            if (isLeapYear(year) == true) {
                num_leap_year++;
                printf("%d\n", year);
            }
        }
        if (num_leap_year == 0) {
            printf("NA\n");
        }
        printf("\n");
    }
    return 0;
}

C++: #include <stdio.h>

void uru(int year);

int main(void)
{
    int a, b;
    int year;
    int j;
    while (1) {
        scanf("%d %d", &a, &b);
        if (a == 0 && b == 0) {
            break;
        } else  {
            for (year = a; year < b; ++year) {
                uru(year);
            }
            if (j == 0) {
                printf("NA\n");
            }
        }
    }
    return 0;
}

void uru(int year)
{
    int j = 0;
    int R4, R100, R400;
    R4 = year % 4;
    R100 = year % 100;
    R400 = year % 400;
    if (R4 == 0 && R100 != 0) {
        printf("%d\n", year);
        ++j;
    } else if (R400 == 0) {
        printf("%d\n", year);
        ++j;
    }
}

C++: /*
    2014.07.04 1230~1240
    C language Lecture week ∞
*/

#include <stdio.h>

int leap_chk ( int year );

int main (void) {
    
    int init;
    int last;
    
    int count;
    
    while (1) {
        
        count = 0;
        
        scanf ( "%d", &init );
        scanf ( "%d", &last );
        
        if ( init == 0 && last == 0 ) {
            break;
        }
        
        for ( int ly = init; ly <= last; ly ++ ) {
            if ( leap_chk ( ly ) ) {
                printf ( "%d\n", ly );
                count ++;
            }
        }
        
        if ( count == 0 ) {
            printf ( "NA\n" );
        }
        printf ( "\n" );
        
    }
    
    return 0;
    
}

int leap_chk ( 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;
    }
    
}

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

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

int main(){
  int a, b;
  bool first = false;
  while(std::cin >> a >> b, a){
    if(first)std::cout << std::endl;
    first = true;
    bool flag = false;
    for (int i = a; i <= b; i++) {
      if(isUruu(i)){
        std::cout << i << std::endl;
        flag = true;
      }
    }
    if(flag == false)std::cout << "NA" << std::endl;
  }
  return 0;
}