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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

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)
	//heap.Init(&pq)
	//heap.Push(&pq, start)
	//pq.Push(start)
	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 pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*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]
			}
			if now==next {
				continue
			}
			next.Turn += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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<map>
#include<queue>

using namespace std;

const int NOT=-1;
int maps[51][51];
int x,y;
int tx,ty;
int kx,ky;
int ans=101;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
int sai[52][52][52][52];
typedef pair<int,int> P;
typedef pair<P,P> PP;

void bfs(){
	queue<PP> pp;
	int a,b,c,d;
	for(a=0;a<=50;a++){
		for(b=0;b<=50;b++){
			for(c=0;c<=50;c++){
				for(d=0;d<=50;d++){
					sai[a][b][c][d]=NOT;
				}
			}
		}
	}
	pp.push(PP(P(tx,ty),P(kx,ky)));
	sai[tx][ty][kx][ky]=0;
	while(pp.size()){
		PP p=pp.front();pp.pop();
		if(p.first.first==p.second.first && p.first.second==p.second.second){
			ans=sai[p.first.first][p.first.second][p.second.first][p.second.second];
			break;
		}
		if(sai[p.first.first][p.first.second][p.second.first][p.second.second]<100){
			for(a=0;a<4;a++){
				int ntx,nty,nkx=p.second.first-dx[a],nky=p.second.second-dy[a];
				
				if(maps[p.first.first+dx[a]][p.first.second+dy[a]]==0 && p.first.first+dx[a]>=1 && p.first.first+dx[a]<=x && p.first.second+dy[a]>=1 && p.first.second+dy[a]<=y){
					ntx=p.first.first+dx[a],nty=p.first.second+dy[a];
				}else ntx=p.first.first,nty=p.first.second;

				if(maps[p.second.first-dx[a]][p.second.second-dy[a]]==0 && p.second.first-dx[a]>=1 && p.second.first-dx[a]<=x && p.second.second-dy[a]>=1 && p.second.second-dy[a]<=y){
					nkx=p.second.first-dx[a],nky=p.second.second-dy[a];
				}else nkx=p.second.first,nky=p.second.second;
				
				if(sai[ntx][nty][nkx][nky]==NOT){
					pp.push(PP(P(ntx,nty),P(nkx,nky)));
					sai[ntx][nty][nkx][nky]=sai[p.first.first][p.first.second][p.second.first][p.second.second]+1;
				}
			}
		}
	}
}

int main(void){
	while(1){
		cin >> x >> y;
		if(x==0 && y==0)break;
		cin >> tx >> ty;
		cin >> kx >> ky;
		int a,b;
		ans=101;
		for(a=1;a<=y;a++){
			for(b=1;b<=x;b++){
				cin >> maps[b][a];
			}
		}
		bfs();
		if(ans<=100)cout << ans << endl;else cout << "NA" << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <algorithm>

#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
using namespace std;


bool table[55][55];

struct state{
	int tx;
	int ty;
	int kx;
	int ky;
	int t;
};

int x,y;
int tx,ty;
int kx,ky;

bool check(int cx,int dx,int cy,int dy){
	if(0<=cx+dx&&cx+dx<x&&0<=cy+dy&&cy+dy<y&&(!table[cx+dx][cy+dy]))
		return true;
	else
		return false;
}

bool visited[55][55][55][55];


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


int bfs(void){
	rep(i,55)rep(j,55)rep(k,55)rep(l,55) visited[i][j][k][l]=false;
	state init;
	init.tx=tx;init.ty=ty;
	init.kx=kx;init.ky=ky;
	init.t=0;
	queue<state> q;

	q.push(init);
	visited[init.tx][init.ty][init.kx][init.ky]=true;

	while(!q.empty()){
	//	cout << "check" << endl;
		state cur=q.front();q.pop();
		if(cur.tx==cur.kx&&cur.ty==cur.ky)
			return cur.t;

		if(cur.t>=100)
			continue;
	//	cout << "check" << endl;
		rep(i,4){
			state next=cur;
			if(check(cur.tx,dx[i],cur.ty,dy[i])){
				next.tx+=dx[i];
				next.ty+=dy[i];
			}
			if(check(cur.kx,dx[(i+2)%4],cur.ky,dy[(i+2)%4])){
				next.kx+=dx[(i+2)%4];
				next.ky+=dy[(i+2)%4];
			}
			next.t++;
			if(!visited[next.tx][next.ty][next.kx][next.ky]){
				visited[next.tx][next.ty][next.kx][next.ky]=true;
				q.push(next);
			}
		//	cout << next.tx << " " << next.ty << endl; 
		//	cout << "check" << endl;
		}
	}
	return -1;
}

int main(void){
	
	while(cin >> x >> y,x|y){
		
		cin >> tx >> ty;
		cin >> kx >> ky;
		tx--;ty--;kx--;ky--;
		rep(i,y)rep(j,x) cin >> table[j][i];
		int res=bfs();
		if(res==-1)
			cout << "NA" << endl;
		else
			cout << res << endl;
	}
	return 0;
}