Go: package main

import (
	"fmt"
	"math"
)

type Position struct {
	X int64
	Y int64
}

func (one Position) Distance(another Position) int64 {
	return int64(math.Abs(float64(one.X-another.X)) + math.Abs(float64(one.Y-another.Y)))
}

type PersonPosition struct {
	Takayuki Position
	Kazuyuki Position
}

func (one PersonPosition) Distance() int64 {
	return one.Takayuki.Distance(one.Kazuyuki)
}

type Status struct {
	Person PersonPosition
	Turn   int64
}

type PQStatus []*Status

func (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

func solve(h, w int64) {
	var tx, ty, kx, ky int64
	fmt.Scan(&tx, &ty, &kx, &ky)
	tx--
	ty--
	kx--
	ky--
	m := make([][]int64, h)
	for i := range m {
		m[i] = make([]int64, w)
		for j := int64(0); j < w; j++ {
			fmt.Scan(&m[i][j])
		}
	}
	start := &Status{Person: PersonPosition{Takayuki: Position{X: tx, Y: ty}, Kazuyuki: Position{X: kx, Y: ky}}, Turn: 0}
	pq := make(PQStatus, 0)
	//heap.Init(&pq)
	//heap.Push(&pq, start)
	pq.Push(start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		now := pq.Pop().(*Status)
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			continue
		}
		memo[now.Person] = now.Turn
		for i := 0; i < 4; i++ {
			next := &Status{}
			*next = *now
			next.Person.Kazuyuki.X += dx[i]
			next.Person.Kazuyuki.Y += dy[i]
			if next.Person.Kazuyuki.X < 0 || next.Person.Kazuyuki.X >= w ||
				next.Person.Kazuyuki.Y < 0 || next.Person.Kazuyuki.Y >= h ||
				m[next.Person.Kazuyuki.Y][next.Person.Kazuyuki.X] == 1 {
				next.Person.Kazuyuki.X -= dx[i]
				next.Person.Kazuyuki.Y -= dy[i]
			}
			next.Person.Takayuki.X -= dx[i]
			next.Person.Takayuki.Y -= dy[i]
			if next.Person.Takayuki.X < 0 || next.Person.Takayuki.X >= w ||
				next.Person.Takayuki.Y < 0 || next.Person.Takayuki.Y >= h ||
				m[next.Person.Takayuki.Y][next.Person.Takayuki.X] == 1 {
				next.Person.Takayuki.X += dx[i]
				next.Person.Takayuki.Y += dy[i]
			}
			next.Turn += 1
			if next.Turn < 100 {
				//heap.Push(&pq, next)
				pq.Push(next)
			}
		}
	}
	if ans == 101 {
		fmt.Println("NA")
	} else {
		fmt.Println(ans)
	}
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

C++: #include <stdio.h>
#include <queue>
using namespace std;

class adres{
public:
	int tkayuki[2],kazuyuki[2],cost;
	
	//adres型の比較
	bool chek(adres the){
		int c = 0;
		int i;
		for(i = 0; i < 2; i++){
			if(the.kazuyuki[i] == kazuyuki[i]){
				c++;
			}
			if(the.tkayuki[i] == tkayuki[i]){
				c++;
			}
		}
		return c == 4;
	}

	//孝幸と和幸の現在地が同じかどうか
	bool takazu(){
		return (tkayuki[1] == kazuyuki[1] && tkayuki[0] == kazuyuki[0]);
	}

	void print(){
		printf("T:%d,%d K:%d,%d C:%d\n",tkayuki[0],tkayuki[1],kazuyuki[0],kazuyuki[1],cost);
	}
};


void syokika();
void in();
void debag();
bool cheklast(adres);
void haba();

//変数宣言
int x,y;
int kx[4] = {1,-1,0,0},ky[4] = {0,0,-1,1},tkx[4] = {-1,1,0,0},tky[4] = {0,0,1,-1};
int i,j,r;
int anser;
bool anserchek;
int map[52][52];
adres start,now,nex;
queue<adres> que,laston;


int main()
{
	
	scanf("%d%d",&x,&y);
	
	while(x != 0 && y != 0){
		//初期化
		syokika();

		//入力
		in();

		//デバック用出力
		debag();

		//幅優先探索
		haba();
		
		scanf("%d%d",&x,&y);
	}

	return 0;
}
void syokika()
{
	int i;

	for(i = 0; i <= x+1; i++){
		map[i][0] = 1;
		map[i][y+1] = 1;
	}
	for(i = 0; i <= y+1; i++){
		map[0][i] = 1;
		map[x+1][i] = 1;
	}
	while(!que.empty()){
		que.pop();
	}
	while(!laston.empty()){
		laston.pop();
	}
	anserchek = false;
	anser = 0;
}
void in()
{
	int tx,ty;
	scanf("%d%d",&tx,&ty);
	start.tkayuki[0] = tx;
	start.tkayuki[1] = ty;
	scanf("%d%d",&tx,&ty);
	start.kazuyuki[0] = tx;
	start.kazuyuki[1] = ty;
	start.cost = 0;
	
	for(i = 1; i <= y; i++){
		for(j = 1; j <= x; j++){
			scanf("%d",&map[j][i]);
		}
	}
}
void debag()
{
	//マップ
	for(i = 0; i <= y+1; i++){
		for(j = 0; j <= x+1; j++){
			printf("%d",map[j][i]);
		}
		printf("\n");
	}
	/*各種関数
	now.kazuyuki[0] = 0;
		now.kazuyuki[1] = 0;
		now.tkayuki[0] = 0;
		now.tkayuki[1] = 1;
		nex = now;
		laston.push(now);
		for(i = 0; i < 10; i++){
			nex.kazuyuki[0]++;
			laston.push(nex);
		}
		now.print();
		printf("%d\n",cheklast(now));
	*/
}
bool cheklast(adres nex){
	int c = 0;
	while(laston.size() != c){
		//キューの中身と引数nexが一致していたら
		if( nex.chek(laston.front()) )	break;
		laston.push(laston.front());
		laston.pop();
		c++;
	}

	return (laston.size() != c);
}
void haba()
{
	que.push(start);
	while(!que.empty()){
		now = que.front();
		now.print();
		que.pop();
		//ゴールかコストが100以上の場合
		if(now.takazu() || now.cost >= 100){
			break;
		}
		//移動処理
		now.cost++;
		for(i = 0; i < 4; i++){
			int nextky = now.kazuyuki[1] + ky[i];
			int nextkx = now.kazuyuki[0] + kx[i];
			int nexttky = now.tkayuki[1] + tky[i];
			int nexttkx = now.tkayuki[0] + tkx[i];
			int c = 0;
			nex = now;
			if(map[nextkx][nextky] == 0 || map[nexttkx][nexttky] == 0){
				if(map[nexttkx][nexttky] == 0){
					nex.tkayuki[0] = nexttkx;
					nex.tkayuki[1] = nexttky;
				}
				if(map[nextkx][nextky] == 0){
					nex.kazuyuki[0] = nextkx;
					nex.kazuyuki[1] = nextky;
				}
				//過去に行った場所でなければ
				if(!cheklast(nex)){
					que.push(nex);
					laston.push(nex);
				}
			}
		}
	}
	if(now.takazu())	printf("%d\n",now.cost);
	else				printf("NA\n");
}