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 ans <= now.Turn {
			continue
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = 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 <bits/stdc++.h>
#include<stdio.h>
using namespace std;
#define FOR(i,k,n) for(int i = (k); i < (n); i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(a) begin(a),end(a)
#define MS(m,v) memset(m,v,sizeof(m))
#define D10  fixed<<setprecision(10)
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int, int> P;
typedef long long ll;
const ll INF = 114514810;
const ll MOD = 1000000007;
const double EPS = 1e-8;
const double PI = acos(-1.0);
struct edge
{
	int from, to, cost;
	bool operator < (const edge& e) const { return cost < e.cost; }
	bool operator >(const edge& e) const { return cost > e.cost; }
};
int dx[] = { -1, 0, 0, 1 }; int dy[] = { 0, -1, 1, 0 };
bool valid(int x, int y, int h, int w) { return (x >= 0 && y >= 0 && x < h&&y < w); }
///*************************************************************************************///
///*************************************************************************************///
///*************************************************************************************///



int main()
{
	int h, w;
	while (cin >> h >> w, h)
	{
		int tx, ty, kx, ky;
		cin >> tx >> ty >> kx >> ky;
		tx--; ty--; kx--; ky--;
		int fld[55][55];
		REP(i, h)REP(j, w) cin >> fld[i][j];
		set<pair<P, P>> memo;
		queue<pair<pair<P, P>, int>> que;
		que.push(make_pair(make_pair(P(ty, tx), P(ky, kx)), 0));
		bool f = true;
		while (que.size())
		{
			memo.insert(que.front().first);
			P tmpt = que.front().first.first;
			P tmpk = que.front().first.second;
			int ttx = tmpt.first, tty = tmpt.second;
			int tkx = tmpk.first, tky = tmpk.second;
			int time = que.front().second;
			que.pop();
			if (time >= 100) break;
			if (ttx == tkx&&tty == tky)
			{
				f = false;
				cout << time << endl;
				break;
			}
			REP(i, 4)
			{
				int ntx = ttx + dx[i], nty = tty + dy[i];
				if (!valid(ntx, nty, h, w) || fld[ntx][nty] == 1)
				{
					ntx = ttx; nty = tty;
				}
				int nkx = tkx - dx[i], nky = tky - dy[i];
				if (!valid(nkx, nky, h, w) || fld[nkx][nky] == 1)
				{
					nkx = tkx; nky = tky;
				}
				P nt = P(ntx, nty), nk = P(nkx, nky);
				if (memo.find(pair<P, P>(nt, nk)) == memo.end())
				{
					que.push(make_pair(make_pair(nt, nk), time + 1));
				}
			}
		}
		if (f) puts("NA");
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <cstring>

#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<30

using namespace std;

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

struct Data
{
	int tx,ty,kx,ky,cost;

	Data(int tx,int ty,int kx,int ky,int cost) : tx(tx),ty(ty),kx(kx),ky(ky),cost(cost) {}
};

int main()
{
	int x,y;
	while(cin >> x >> y)
	{
		if(x == 0 && y == 0) break;

		int tx,ty,kx,ky;
		cin >> tx >> ty >> kx >> ky;

		tx--;
		ty--;
		kx--;
		ky--;

		int field[50][50];
		memset(field,0,sizeof(field));

		rep(i,y) rep(j,x) cin >> field[i][j];

	   	bool used[51][51][51][51];
		rep(i,51) rep(j,51) rep(k,51) rep(l,51) used[i][j][k][l] = false;
		used[tx][ty][kx][ky] = true;

		queue<Data> que;
		que.push(Data(tx,ty,kx,ky,0));
		
		bool flag = false;
		int ans;

		while(que.size())
		{
			Data data = que.front();
			que.pop();

			if(data.cost >= 100) break;

			if(data.tx == data.kx && data.ty == data.ky)
			{
				flag = true;
				ans = data.cost;
				break;
			}

			rep(i,4)
			{
				int ntx = data.tx + dx[i];
				int nty = data.ty + dy[i];
				int nkx = data.kx + dx[(i+2)%4];
				int nky = data.ky + dy[(i+2)%4];

				Data nd(data.tx,data.ty,data.kx,data.ky,data.cost+1);

				if(0 <= ntx && ntx < x && 0 <= nty && nty < y && field[ntx][nty] == 0)
				{
					nd.tx = ntx;
					nd.ty = nty;
				}

				if(0 <= nkx && nkx < x && 0 <= nky && nky < y && field[nkx][nty] == 0)
				{
					nd.kx = nkx;
					nd.ky = nky;
				}

				if(!used[nd.tx][nd.ty][nd.kx][nd.ky])
				{
					used[nd.tx][nd.ty][nd.kx][nd.ky] = true;
					que.push(nd);
				}
			}

		}

		if(flag) cout << ans << endl;
		else cout << "NA" << endl;
	}
}