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
		}
		if ans<=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;
queue<int> tx, ty, kx, ky;
int d[50][50];
void move(void);
void clean(void);
int main(void)
{
	int x, y, X, Y,i,j;
	while (1) {
		for (i = 0; i < 50; i++) {
			for (j = 0; j < 50; j++) {
				d[i][j] = 1;
			}
		}
		scanf("%d %d", &X, &Y);   //????????????
		if (X == 0 && Y == 0) break;
		scanf("%d %d", &x, &y);   //????????????
		tx.push(x);  ty.push(y);
		scanf("%d %d", &x, &y);   //????????????
		kx.push(x);  ky.push(y);
		for (i = 1; i <= Y; i++) {
			for (j = 1; j <= X; j++) {
				scanf("%d", &d[i][j]);
			}
		}
		move();
		clean();
	}
	return 0;
}

void move()
{
	int cnt = 0,count=0,s=4;
	int m[4][4]={-1,1,0,0,      //taka y
				 0,0,-1,1,      //taka x
				 1,-1,0,0,      //kazu y
				 0,0,1,-1};     //kazu x
	while (1) {
		if (tx.back() == kx.back() && ty.back() == ky.back()) {
			printf("A%d\n", count);
			break;
		}
		if (d[ty.front() + m[0][cnt%4]][tx.front() + m[1][cnt%4]] == 0) {              //?????????
			tx.push(tx.front() + m[1][cnt%4]);
			ty.push(ty.front() + m[0][cnt%4]);
		}
		else if (d[ty.front() + m[0][cnt%4]][tx.front() + m[1][cnt%4]] == 1) {
			tx.push(tx.front());
			ty.push(ty.front());
		}
		if (d[ky.front() + m[2][cnt%4]][kx.front() + m[3][cnt%4]] == 0) {              //?????????
			kx.push(kx.front() + m[3][cnt%4]);
			ky.push(ky.front() + m[2][cnt%4]);
		}
		else if (d[ky.front() + m[2][cnt%4]][kx.front() + m[3][cnt%4]] == 1) {
			kx.push(kx.front());
			ky.push(ky.front());
		}

		cnt++;
		
		if(cnt == s){
			count++;
			s = s * s;
			cnt = 0;
			printf("\nQQQ\n");
		}
		//printf("%d ??????x.%d y.%d   ??????x.%d y.%d\n",cnt%4, tx.back(),ty.back(), kx.back(),ky.back());
		//printf("X %d %d\nY %d %d",kx.front(),m[3][cnt%4],ky.front(),m[2][cnt%4]);
		if (tx.back() == kx.back() && ty.back() == ky.back()) {
			printf("%d\n", count+1);
			break;
		}
	
		if(cnt % 4 == 0 && cnt !=0){
			tx.pop();  ty.pop();  kx.pop();  ky.pop();
		}
		if (count >= 100) {
			printf("NA\n");
			break;
		}
	}
}

void clean(void)
{
	while (!tx.empty()) {
		tx.pop();
	}
	while (!ty.empty()) {
		ty.pop();
	}
	while (!kx.empty()) {
		kx.pop();
	}
	while (!ky.empty()) {
		ky.pop();
	}
}

C++: #include <bits/stdc++.h>
using namespace std;

#define for_(i,a,b) for(int i=(a);i<(b);++i)

const int dx[4] = {0,1,0,-1};
const int dy[4] = {-1,0,1,0};

bool in_range(int x, int mn, int mx) { return mn <= x && x < mx; }
bool in_range(int x, int y, int w, int h) { return in_range(x, 0, w) && in_range(y, 0, h); }

struct State { int step, x1, y1, x2, y2; };

int W, H, tx, ty, kx, ky, grid[55][55];
int dst[55][55][55][55];

void solve() {
	memset(dst, -1, sizeof(dst));
	
	queue< State > que;
	que.push(State{0, tx, ty, kx, ky});
	dst[ty][tx][ky][kx] = 0;
	
	while (!que.empty()) {
		State s = que.front(); que.pop();
		
		if (s.step >= 100) break;
				
		if (s.x1 == s.x2 && s.y1 == s.y2) {
			cout << s.step << endl;
			return;
		}
		
		for_(d,0,4) {
			int nx1 = s.x1 + dx[d], ny1 = s.y1 + dy[d];
			int nx2 = s.x2 + dx[(d + 2) % 4], ny2 = s.y2 + dy[(d + 2) % 4];
			
			if (!in_range(nx1, ny1, W, H)) { nx1 = s.x1; ny1 = s.y1; }
			if (grid[ny1][nx1] == 1) { nx1 = s.x1; ny1 = s.y1; }
			
			if (!in_range(nx2, ny2, W, H)) { nx2 = s.x2; ny2 = s.y2; }
			if (grid[ny2][nx2] == 1) { nx2 = s.x2; ny2 = s.y2; }
			
			if (dst[ny1][nx1][ny2][nx2] == -1) {
				dst[ny1][nx1][ny2][nx2] = s.step + 1;
				que.push(State{s.step + 1, nx1, ny1, nx2, ny2});
			}
		}
	}
	
	cout << "NA" << endl;
}

int main() {
	while (cin >> W >> H, W) {
		cin >> tx >> ty;
		--tx; --ty;
		cin >> kx >> ky;
		--kx; --ky;
		for_(i,0,H) for_(j,0,W) cin >> grid[i][j];
		solve();
	}
}