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++: //2015/7/
#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;

bool che[50][50][50][50];

struct Person{ int x, y; };

struct Twin{ Person T, K; int cnt; };

bool isOK(Twin t){
	if (t.T.x == t.K.x && t.T.y == t.K.y){
		return true;
	}
	return false;
}

void initCheck(Twin t){
	for (int a = 0; a < 50; a++){
		for (int b = 0; b < 50; b++){
			for (int c = 0; c < 50; c++){
				for (int d = 0; d < 50; d++){
					che[a][b][c][d] = false;
				}
			}
		}
	}
	che[t.T.x - 1][t.T.y - 1][t.K.x - 1][t.K.y - 1] = true;
}

bool Check(Twin t){
	if (che[t.T.x - 1][t.T.y - 1][t.K.x - 1][t.K.y - 1]){
		return false;
	}
	che[t.T.x - 1][t.T.y - 1][t.K.x - 1][t.K.y - 1] = true;
	return true;
}

int main(){
	int x,y,d[52][52];
	Twin tw;
	while (cin >> x >> y){
		if (x == 0 && y == 0){
			break;
		}

		cin >> tw.T.x >> tw.T.y >> tw.K.x >> tw.K.y;

		tw.cnt = 0;
		for (int i = 0; i < y + 2; i++){
			for (int j = 0; j < x + 2; j++){
				d[j][i] = 1;
			}
		}

		for (int i = 1; i <= y; i++){
			for (int j = 1; j <= x; j++){
				cin >> d[j][i];
			}
		}

		queue<Twin> que;
		que.push(tw);

		initCheck(tw);

		while (1){
			if (que.empty()){
				cout << "NA\n";
				break;
			}
			Twin T = que.front();
			que.pop();

			if (T.cnt >= 100){
				cout << "NA\n";
				break;
			}
			if (isOK(T)){
				cout << T.cnt << endl;
				break;
			}
			T.cnt += 1;
			/*for (int i = 0; i < y + 2; i++){
				for (int j = 0; j < x + 2; j++){
					if (j == T.T.x && i == T.T.y){
						cout << "T";
					}
					else if (j == T.K.x&&i == T.K.y){
						cout << "K";
					}
					else
						cout << d[j][i];
				}
				cout << endl;
			}*/

			//T??????,K??????
			Twin tmp = T;
			if (d[tmp.T.x][tmp.T.y - 1] == 0)
			{
				tmp.T.y -= 1;
			}
			if (d[tmp.K.x][tmp.K.y + 1] == 0){
				tmp.K.y += 1;
			}
			if (Check(tmp)){
				que.push(tmp);
			}

			//T??????,K??????
			tmp = T;
			if (d[tmp.T.x][tmp.T.y + 1] == 0)
			{
				tmp.T.y += 1;
			}
			if (d[tmp.K.x][tmp.K.y - 1] == 0){
				tmp.K.y -= 1;
			}
			if (Check(tmp)){
				que.push(tmp);
			}

			//T??±???,K?\????
			tmp = T;
			if (d[tmp.T.x + 1][tmp.T.y] == 0)
			{
				tmp.T.x += 1;
			}
			if (d[tmp.K.x - 1][tmp.K.y] == 0){
				tmp.K.x -= 1;
			}
			if (Check(tmp)){
				que.push(tmp);
			}

			//T?\????,K??±???
			tmp = T;
			if (d[tmp.T.x - 1][tmp.T.y] == 0)
			{
				tmp.T.x -= 1;
			}
			if (d[tmp.K.x + 1][tmp.K.y] == 0){
				tmp.K.x += 1;
			}
			if (Check(tmp)){
				que.push(tmp);
			}

		}
	}
	return 0;
}

C++: #include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<queue>
#include<iostream>
using namespace std;
struct data{
    int x;
    int y;
    int u;
    int v;
    int t;
};

bool vis[60][60][60][60] = {};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
int main(void){
    int w,h;
    while(cin>>w>>h,w){
        int x,y,u,v;
        cin>>x>>y>>u>>v;
        bool screen[60][60] = {};
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin>>screen[i][j];
            }
        }
        data D;
        D.x = x,D.y = y;
        D.u = u,D.v = v;
        D.t = 0;
        queue<data> Q;
        Q.push(D);

        while(!Q.empty()){
            data E = Q.front();Q.pop();

            if(E.x == E.u&&E.y == E.v){
                cout<<E.t<<endl;
                goto e;
            }
            if(E.t>99)break;
            for(int i = 0;i < 4;i++){

                    data F = E;
                    F.t++;
                    F.x+=dx[i],F.y+=dy[i],F.u+=dx[(i+2)%4],F.v+=dy[(i+2)%4];
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h)){
                        F.x = E.x,F.y = E.y;
                    }
                    if(screen[F.x][F.y])F.x = E.x,F.y = E.y;
                    if(!(0<=F.u&&F.u<w&&0<=F.v&&F.v<h)){
                        F.u = E.u,F.v = E.v;
                    }
                    if(screen[F.u][F.v])F.u = E.u,F.v = E.v;
                    if(vis[F.x][F.y][F.u][F.v]||vis[F.u][F.v][F.x][F.y])continue;

                    vis[F.x][F.y][F.u][F.v] = true;
                    vis[F.u][F.v][F.x][F.y] = true;
                    Q.push(F);

            }

        }
        cout<<"NA"<<endl;
        e:;
    }


    return 0;
}