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 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)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(102)
	for len(pq) > 0 {
		now := pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}

		if _, ok := memo[now.Person]; ok {
			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++
			if next.Turn <= 100 {
				pq = append(pq, next)
			}
		}
	}
	if ans == 102 {
		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 <algorithm>
#include <iostream>
#include <stack>
#include <vector>
#include <math.h>
#include <queue>

using namespace std;

bool** checkTable;

int width,height;

struct Info{
	Info(){
		a_x = a_y = b_x = b_y = count = 0;
	}
	Info(short arg_a_x,short arg_a_y,short arg_b_x,short arg_b_y,short arg_count){
		a_x = arg_a_x;
		a_y = arg_a_y;
		b_x = arg_b_x;
		b_y = arg_b_y;
		count = arg_count;
	}

	short a_x,a_y,b_x,b_y,count;
};


bool rangeCheck(int y,int x){
	if(x >= 0 && x <= width-1 && y >= 0 && y <= height-1)return true;
	else{
		return false;
	}
}

void func(){

	for(int i = 0; i <= 50*(height-1)+(width-1); i++){
		for(int k = 0; k <= 50*(height-1)+(width-1); k++)checkTable[i][k] = false;
	}

	int a_x,a_y,b_x,b_y;

	scanf("%d %d",&a_x,&a_y);
	scanf("%d %d",&b_x,&b_y);

	a_x--;
	a_y--;
	b_x--;
	b_y--;

	checkTable[50*a_y+a_x][50*b_y+b_x] = true;

	short map[height][width];

	for(int i = 0; i < height; i++){
		for(int k = 0; k < width; k++)scanf("%hd",&map[i][k]);
	}

	queue<Info> Q;

	Q.push(Info(a_x,a_y,b_x,b_y,0));

	bool FLG = false;
	Info tmp;
	while(!Q.empty()){
		tmp = Q.front();
		Q.pop();

		if(tmp.a_x == tmp.b_x && tmp.a_y == tmp.b_y && tmp.count <= 99){
			printf("%d\n",tmp.count);
			FLG = true;
			break;
		}

		if(tmp.count == 100)continue;

		if((rangeCheck(tmp.a_y,tmp.a_x-1) == false || map[tmp.a_y][tmp.a_x-1] == 1)&&
				(rangeCheck(tmp.b_y,tmp.b_x+1) == false || map[tmp.b_y][tmp.b_x+1] == 1)){
			//Do nothing
		}else if((rangeCheck(tmp.a_y,tmp.a_x-1) == true && map[tmp.a_y][tmp.a_x-1] == 0)&&
				(rangeCheck(tmp.b_y,tmp.b_x+1) == false || map[tmp.b_y][tmp.b_x+1] == 1)){

			if(checkTable[50*tmp.a_y+tmp.a_x-1][50*tmp.b_y+tmp.b_x] == false){

				if(100-tmp.count >= (abs((tmp.a_x-1)-tmp.b_x)+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x-1][50*tmp.b_y+tmp.b_x] = true;
					Q.push(Info(tmp.a_x-1,tmp.a_y,tmp.b_x,tmp.b_y,tmp.count+1));
				}
			}

		}else if((rangeCheck(tmp.a_y,tmp.a_x-1) == false || map[tmp.a_y][tmp.a_x-1] == 1)&&
				(rangeCheck(tmp.b_y,tmp.b_x+1) == true && map[tmp.b_y][tmp.b_x+1] == 0)){ //B????????????????????´???

			if(checkTable[50*tmp.a_y+tmp.a_x][50*tmp.b_y+tmp.b_x+1] == false){

				if(100-tmp.count >= (abs(tmp.a_x-(tmp.b_x+1))+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x][50*tmp.b_y+tmp.b_x+1] = true;
					Q.push(Info(tmp.a_x,tmp.a_y,tmp.b_x+1,tmp.b_y,tmp.count+1));
				}
			}

		}else{
			if(checkTable[50*tmp.a_y+tmp.a_x-1][50*tmp.b_y+tmp.b_x+1] == false){

				if(100-tmp.count >= (abs((tmp.a_x-1)-(tmp.b_x+1))+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x-1][50*tmp.b_y+tmp.b_x+1] = true;
					Q.push(Info(tmp.a_x-1,tmp.a_y,tmp.b_x+1,tmp.b_y,tmp.count+1));
				}
			}
		}

		if((rangeCheck(tmp.a_y,tmp.a_x+1) == false || map[tmp.a_y][tmp.a_x+1] == 1)&&
				(rangeCheck(tmp.b_y,tmp.b_x-1) == false || map[tmp.b_y][tmp.b_x-1] == 1)){
			//Do nothing
		}else if((rangeCheck(tmp.a_y,tmp.a_x+1) == true && map[tmp.a_y][tmp.a_x+1] == 0)&&
				(rangeCheck(tmp.b_y,tmp.b_x-1) == false || map[tmp.b_y][tmp.b_x-1] == 1)){

			if(checkTable[50*tmp.a_y+tmp.a_x+1][50*tmp.b_y+tmp.b_x] == false){

				if(100-tmp.count >= (abs((tmp.a_x+1)-tmp.b_x)+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x+1][50*tmp.b_y+tmp.b_x] = true;
					Q.push(Info(tmp.a_x+1,tmp.a_y,tmp.b_x,tmp.b_y,tmp.count+1));
				}
			}

		}else if((rangeCheck(tmp.a_y,tmp.a_x+1) == false || map[tmp.a_y][tmp.a_x+1] == 1)&&
				(rangeCheck(tmp.b_y,tmp.b_x-1) == true && map[tmp.b_y][tmp.b_x-1] == 0)){

			if(checkTable[50*tmp.a_y+tmp.a_x][50*tmp.b_y+tmp.b_x-1] == false){

				if(100-tmp.count >= (abs(tmp.a_x-(tmp.b_x-1))+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x][50*tmp.b_y+tmp.b_x-1] = true;
					Q.push(Info(tmp.a_x,tmp.a_y,tmp.b_x-1,tmp.b_y,tmp.count+1));
				}
			}

		}else{
			if(checkTable[50*tmp.a_y+tmp.a_x+1][50*tmp.b_y+tmp.b_x-1] == false){

				if(100-tmp.count >= (abs((tmp.a_x+1)-(tmp.b_x-1))+abs(tmp.a_y-tmp.b_y))/2){
					checkTable[50*tmp.a_y+tmp.a_x+1][50*tmp.b_y+tmp.b_x-1] = true;
					Q.push(Info(tmp.a_x+1,tmp.a_y,tmp.b_x-1,tmp.b_y,tmp.count+1));
				}
			}
		}


		if((rangeCheck(tmp.a_y-1,tmp.a_x) == false || map[tmp.a_y-1][tmp.a_x] == 1)&&
				(rangeCheck(tmp.b_y+1,tmp.b_x) == false || map[tmp.b_y+1][tmp.b_x] == 1)){
			//Do nothing
		}else if((rangeCheck(tmp.a_y-1,tmp.a_x) == true && map[tmp.a_y-1][tmp.a_x] == 0)&&
				(rangeCheck(tmp.b_y+1,tmp.b_x) == false || map[tmp.b_y+1][tmp.b_x] == 1)){

			if(checkTable[50*(tmp.a_y-1)+tmp.a_x][50*tmp.b_y+tmp.b_x] == false){

				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs((tmp.a_y-1)-tmp.b_y))/2){
					checkTable[50*(tmp.a_y-1)+tmp.a_x][50*tmp.b_y+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y-1,tmp.b_x,tmp.b_y,tmp.count+1));
				}
			}

		}else if((rangeCheck(tmp.a_y-1,tmp.a_x) == false || map[tmp.a_y-1][tmp.a_x] == 1)&&
				(rangeCheck(tmp.b_y+1,tmp.b_x) == true && map[tmp.b_y+1][tmp.b_x] == 0)){

			if(checkTable[50*tmp.a_y+tmp.a_x][50*(tmp.b_y+1)+tmp.b_x] == false){

				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs(tmp.a_y-(tmp.b_y+1)))/2){
					checkTable[50*tmp.a_y+tmp.a_x][50*(tmp.b_y+1)+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y,tmp.b_x,tmp.b_y+1,tmp.count+1));
				}
			}

		}else{
			if(checkTable[50*(tmp.a_y-1)+tmp.a_x][50*(tmp.b_y+1)+tmp.b_x] == false){
				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs((tmp.a_y-1)-(tmp.b_y+1)))/2){
					checkTable[50*(tmp.a_y-1)+tmp.a_x][50*(tmp.b_y+1)+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y-1,tmp.b_x,tmp.b_y+1,tmp.count+1));
				}
			}
		}


		if((rangeCheck(tmp.a_y+1,tmp.a_x) == false || map[tmp.a_y+1][tmp.a_x] == 1)&&
				(rangeCheck(tmp.b_y-1,tmp.b_x) == false || map[tmp.b_y-1][tmp.b_x] == 1)){
			//Do nothing
		}else if((rangeCheck(tmp.a_y+1,tmp.a_x) == true && map[tmp.a_y+1][tmp.a_x] == 0)&&
				(rangeCheck(tmp.b_y-1,tmp.b_x) == false || map[tmp.b_y-1][tmp.b_x] == 1)){

			if(checkTable[50*(tmp.a_y+1)+tmp.a_x][50*tmp.b_y+tmp.b_x] == false){

				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs((tmp.a_y+1)-tmp.b_y))/2){
					checkTable[50*(tmp.a_y+1)+tmp.a_x][50*tmp.b_y+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y+1,tmp.b_x,tmp.b_y,tmp.count+1));
				}
			}

		}else if((rangeCheck(tmp.a_y+1,tmp.a_x) == false || map[tmp.a_y+1][tmp.a_x] == 1)&&
				(rangeCheck(tmp.b_y-1,tmp.b_x) == true && map[tmp.b_y-1][tmp.b_x] == 0)){

			if(checkTable[50*tmp.a_y+tmp.a_x][50*(tmp.b_y-1)+tmp.b_x] == false){

				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs(tmp.a_y-(tmp.b_y-1)))/2){
					checkTable[50*tmp.a_y+tmp.a_x][50*(tmp.b_y-1)+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y,tmp.b_x,tmp.b_y-1,tmp.count+1));
				}
			}

		}else{

			if(checkTable[50*(tmp.a_y+1)+tmp.a_x][50*(tmp.b_y-1)+tmp.b_x] == false){

				if(100-tmp.count >= (abs(tmp.a_x-tmp.b_x)+abs((tmp.a_y+1)-(tmp.b_y-1)))/2){
					checkTable[50*(tmp.a_y+1)+tmp.a_x][50*(tmp.b_y-1)+tmp.b_x] = true;
					Q.push(Info(tmp.a_x,tmp.a_y+1,tmp.b_x,tmp.b_y-1,tmp.count+1));
				}
			}
		}
	}

	if(!FLG){
		printf("NA\n");
	}

}


int main(){


	checkTable = new bool*[2500];
	for(int i = 0; i < 2500; i++){
		checkTable[i] = new bool[2500];
	}

	while(true){
		scanf("%d %d",&width,&height);
		if(width == 0 && height == 0)break;

		func();
	}

    return 0;
}