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 := &Status{}
		*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<utility>
#include<queue>
using namespace std;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
int main() {
	int W, H, tx, ty, kx, ky;
	bool d[52][52];
	bool memo[52][52][52][52];
	while (true) {
		cin >> W >> H;
		if (W == 0)break;
		for (int i = 0; i < 52; i++) {
			for (int j = 0; j < 52; j++) {
				d[i][j] = 1;
				for (int k = 0; k < 52; k++) {
					for (int l = 0; l < 52; l++) {
						memo[i][j][k][l] = false;
					}
				}
			}
		}
		cin >> tx >> ty >> kx >> ky;
		for (int i = 1; i < H + 1; i++) {
			for (int j = 1; j < W + 1; j++) {
				cin >> d[j][i];
			}
		}
		pair<pair<int, int>, pair<int, int> >num;
		num.first.first = tx;
		num.first.second = ty;
		num.second.first = kx;
		num.second.second = ky;
		queue<pair<pair<int, int>, pair<int, int> > > q;
		q.push(num);
		int qsize = q.size();
		int loopcount = 0;
		while (!q.empty()) {
			num = q.front();
			q.pop();
			if (qsize == 0) {
				qsize = q.size();
				loopcount++;
				if (loopcount == 100) {
					cout << "NA" << endl;
					break;
				}
			}
			qsize--;
			if (memo[num.first.first][num.first.second][num.second.first][num.second.second]) {
				continue;
			}
			else {
				memo[num.first.first][num.first.second][num.second.first][num.second.second] = true;
			}
			if (num.first.first == num.second.first && num.first.second == num.second.second) {
				cout << loopcount << endl;
				break;
			}
			for (int i = 0; i < 4; i++) {
				pair<pair<int, int>, pair<int, int> >copy;
				copy = num;
				copy.first.first += dx[i];
				copy.first.second += dy[i];
				if (d[copy.first.first][copy.first.second]) {
					copy.first.first -= dx[i];
					copy.first.second -= dy[i];
				}
				copy.second.first += -dx[i];
				copy.second.second += -dy[i];
				if (d[copy.second.first][copy.second.second]) {
					copy.second.first -= -dx[i];
					copy.second.second -= -dy[i];
				}
				q.push(copy);
			}
		}
		if (q.size() == 0) {
			cout << "NA" << endl;
		}
	}
	return 0;
}

C++: /*??£?¨?*/
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<queue>
#include<string.h>
#include<string>
#include<vector>
using namespace std;
struct X
{
	int tx, ty, t, kx, ky;
};
static int java[51][51][51][51];
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
int main()
{
	while (1)
	{
		int w, h, map[52][52];
		int mx[] = { 0,1,0,-1 }, my[] = { 1,0,-1,0 };
		queue<X> que;
		X c;
		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)
		{
			rep(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 (1)
		{
			c = que.front();
			que.pop();
			java[c.tx][c.ty][c.kx][c.ky] = 1;
			if (c.tx == c.kx&&c.ty == c.ky&&c.t >= 100)
			{
				break;
			}
			c.t++;
			rep(i, 4)
			{
				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)
				{
					c.tx += mx[i];
					c.ty += my[i];
					c.kx -= mx[i];
					c.ky -= my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.tx -= mx[i];
					c.ty -= my[i];
					c.kx += mx[i];
					c.ky += my[i];
				}
				if (java[c.tx][c.ty][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 1 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
				{
					c.kx -= mx[i];
					c.ky -= my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.kx += mx[i];
					c.ky += my[i];
				}
				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]] == 1)
				{
					c.tx += mx[i];
					c.ty += my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.tx -= mx[i];
					c.ty -= my[i];
				}
			}
		}
		if (c.t < 100)
			cout << c.t << endl;
		else
			cout << "NA" << endl;
	}
	return 0;
}