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 <iostream>
#include <queue>
#include <map>
using namespace std;
 
class Point2{
public:
    int tx;
    int ty;
    int kx;
    int ky;
};
 
int mk(Point2 p)        
{
    return (((p.tx-1)*50+(p.ty-1))*50+(p.kx-1))*50+(p.ky-1);
}
 
int main()
{
    while(true){
        int W, H;
        cin >> W >> H;
 
        if(W==0 && H==0)
            break;
 
        Point2 p;
        cin >> p.tx >> p.ty;
        cin >> p.kx >> p.ky;
 
        int d[52][52];
        for(int y=0; y<=H+1; y++){
            for(int x=0; x<=W+1; x++){
                d[y][x] = 1;           
            }
        }
 
        for(int y=1; y<=H; y++){
            for(int x=1; x<=W; x++){
                cin >> d[y][x];
            }
        }
 
        queue<Point2> que;        
        que.push(p);
 
        map<int, int> n;        
        n[mk(p)] = 0;
 
        while(true){
            if(que.empty()){           
                cout << "NA" << endl;
                break;
            }
 
            p = que.front();
            que.pop();
 
            if(n[mk(p)]>=100){      
                cout << "NA" << endl;
                break;
            }
 
            if(p.tx==p.kx && p.ty==p.ky){       
                cout << n[mk(p)] << endl;
                break;
            }
 
            Point2 q;
 
            q = p;
            if(d[q.ty][q.tx+1]==0){
                q.tx = q.tx+1;
            }
            if(d[q.ky][q.kx-1]==0){
                q.kx = q.kx-1;
            }
            if(n.find(mk(q))==n.end()){
                que.push(q);
                n[mk(q)] = n[mk(p)]+1;
            }
 
            q = p;
            if(d[q.ty][q.tx-1]==0){
                q.tx = q.tx-1;
            }
            if(d[q.ky][q.kx+1]==0){
                q.kx = q.kx+1;
            }
            if(n.find(mk(q))==n.end()){
                que.push(q);
                n[mk(q)] = n[mk(p)]+1;
            }
 
            q = p;
            if(d[q.ty+1][q.tx]==0){
                q.ty = q.ty+1;
            }
            if(d[q.ky-1][q.kx]==0){
                q.ky = q.ky-1;
            }
            if(n.find(mk(q))==n.end()){
                que.push(q);
                n[mk(q)] = n[mk(p)]+1;
            }
 
            q = p;
            if(d[q.ty-1][q.tx]==0){
                q.ty = q.ty-1;
            }
            if(d[q.ky+1][q.kx]==0){
                q.ky = q.ky+1;
            }
            if(n.find(mk(q))==n.end()){
                que.push(q);
                n[mk(q)] = n[mk(p)]+1;
            }
        }
    }
 
    return 0;
}

C++: /*??£?¨?*/
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<queue>
#include<string.h>
#include<string>
#include<vector>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
struct X
{
	int tx, ty, t, kx, ky;
};
int java[52][52][52][52] = { 0 };

int check(int, int, int, int, int, int, int, int);

int main()
{
	int w, h, map[52][52] = { 0 };
		int mx[4] = { 0,1,0,-1 }, my[4] = { 1,0,-1,0 };
		while (1)
		{
			queue<X> que;
			X c,as;
			cin >> w >> h;
			if (w == 0 && h == 0)
				break;
			memset(java, 0, sizeof(java));
			cin >> c.tx >> c.ty >> c.kx >> c.ky;
			c.t = 0;
			que.push(c);
			rep1(i, h)
			{
				rep1(j, w)
				{
					cin >> map[i][j];
				}
			}
			/*?£???????*/
			rep(i, h + 2)//n???????????°,m????¨??????°
			{
				map[i][0] = 1;
				map[i][w + 1] = 1;
			}
			rep(i, w + 2)
			{
				map[0][i] = 1;
				map[h + 1][i] = 1;
			}
			while (!que.empty())
			{
				c = que.front();
				que.pop();
				java[c.tx][c.ty][c.kx][c.ky] = 1;


				//cout << "T" << c.tx << " " << c.ty << endl;
				//cout << "K" << c.kx << " " << c.ky << endl;

			//	c.t++;

				if (c.tx == c.kx&&c.ty == c.ky||c.t >= 100)
				{
					break;
				}
				
				rep(i, 4)
				{
					as = c;

					if (check(c.tx, c.ty, c.kx, c.ky, mx[i], my[i], h, w) == 1)
					{
						//cout << "T" << c.tx << " " << c.ty << endl;
						//cout << "K" << c.kx << " " << c.ky << endl;

						if (java[c.tx + mx[i]][c.ty + my[i]][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
						{
							++as.t;

							as.tx = c.tx + mx[i];
							as.ty = c.ty + my[i];
							as.kx = c.kx - mx[i];
							as.ky = c.ky - my[i];
							que.push(as);
							java[as.tx][as.ty][as.kx][as.ky] = 1;
						}
						else if (java[c.tx][c.ty][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] != 0 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
						{
							++as.t;

							as.kx = c.kx - mx[i];
							as.ky = c.ky - my[i];
							que.push(as);
							java[as.tx][as.ty][as.kx][as.ky] = 1;
						}
						else if (java[c.tx + mx[i]][c.ty + my[i]][c.kx][c.ky] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] != 0)
						{
							++as.t;

							as.tx = c.tx + mx[i];
							as.ty = c.ty + my[i];
							que.push(as);
							java[as.tx][as.ty][as.kx][as.ky] = 1;
						}
					}
				}
			}
			if (c.tx == c.kx&&c.ty == c.ky)
				cout << c.t << endl;
			else
				cout << "NA" << endl;
		}
	return 0;
}


int check(int tx, int ty, int kx, int ky, int mx, int my ,int h ,int w )
{
	tx += mx;
	kx -= mx;

	ty += my;
	ky -= my;

	/*
	if (tx > w || kx > w || ty > h || ky > h || tx < 1 || kx < 1 || ty < 1 || ky < 1)
	{
		return 0;
	}
	*/

	if ((tx > w || ty > h || tx < 1 || ty < 1) && (kx > w || ky > h || kx < 1 || ky < 1))
	{
		return 0;
	}

	return 1;
}