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<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[50][50][50][50];
int main(){
	PP S;
	queue<PP> P;
	int  w,h,b;
	int d=0,i=0,j=0,l=-1,D[52][52];
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&w,&h);
	while(w!=0&&h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1; //??¨????????????????????\?????? 
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;

		if(D[S.tx][S.ty]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.kx][S.ky]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

C++: #include<iostream>
#include<queue>
#include<cstdio>
#include<cstring>

using namespace std;

#define MAX 51

int xy[MAX][MAX];
int cost[MAX][MAX][MAX][MAX];
int X,Y;

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

struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int co;
  state(){}
  state(int tx,int ty,int kx,int ky,int co):
    tx(tx),ty(ty),kx(kx),ky(ky),co(co){}
};

int solve(int tx,int ty,int kx,int ky){

  memset(cost,101,sizeof(cost));

  queue<state> q;
  q.push( state(tx,ty,kx,ky,0) );

  while( !q.empty() ){
    state p=q.front();
    q.pop();

    if(p.co==100){
      break;
    }

    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;

    for(int i=0;i<4;i++){
      
      if(kx+dx[i]*-1 < 0 || ky+dy[i]*-1 <0 || kx+dx[i]*-1 >= X || ty+dy[i]*-1 >= Y || 
	 tx+dx[i] < 0 || ty+dy[i] <0 || tx+dx[i] >= X || ty+dy[i] >= Y )
	continue;

      cost[tx][ty][kx][ky]=p.co;

      if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] < p.co)
	continue;

      if( xy[ty+dy[i]][tx+dx[i]]==1 || xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	continue;
      
      if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1)
	return p.co+1;

      q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );

    }
  }
  return -1;
} 

main(){
  
  int i,j;
  int kx,ky,tx,ty;
  int n;

  while(1){
    
    cin >> X >> Y;

    if(X==0 && Y==0) break;
    
    cin >> tx >> ty;
    cin >> kx >> ky;
    
    for(i=0;i<Y;i++){
      for(j=0;j<X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx-1,ty-1,kx-1,ky-1);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<queue>
#include<cstring>
using namespace std;

bool went[50 + 10][50 + 10][50 + 10][50 + 10] = { 0 };

int map[50 + 10][50 + 10]/* = { 0 }*/;

int gx[] = { 1,0,-1,0,-1,0,1,0 };
int gy[] = { 0,1,0,-1,0,-1,0,1 };

struct ST
{
	int tx, ty;
	int kx, ky;
	int tim=0;
};

bool ChekNow(ST);


ST GoMap(ST, int);

void test(ST ex, int h, int w)
{
	int i, j;
	cout << endl;
	for (i = 1; i <= h; i++)
	{
		for (j = 1; j <= w; j++)
		{
			if ((i == ex.ky && j == ex.kx) || (i == ex.ty && j == ex.tx))
				cout << "*";
			else cout << map[i][j];
		}
		cout << endl;
	}
	cout << ex.tim << endl;
}


int main()
{
	ST now,tmp;

	queue <ST> nx;


	int w, h;
	int tsx, tsy;
	int ksx, ksy;

	bool flg;
	int i, j;

	while (cin >> w >> h, w != 0 && h != 0)
	{
		flg = true;

		cin >> tsx >> tsy;
		cin >> ksx >> ksy;
		
		for (i = 1; i <= h; i++)
		{
			map[i][0] = map[i][w + 1] = 1;

			for (j = 1; j <= w; j++)
			{
				cin >> map[i][j];
			}
		}

		for (i = 0; i <= w + 1; i++)
		{
			map[0][i] = 1;
			map[h + 1][i] = 1;
		}


		now.tx = tsx;
		now.ty = tsy;
		now.kx = ksx;
		now.ky = ksy;
		now.tim = 0;

		nx.push(now);

		while (!nx.empty()  && now.tim<100)
		{
			now = nx.front();
			nx.pop();

			/*
			if (now.tim >= 100)
			{
				break;
			}
			*/


			//if (ChekNow(now))
			//{
			//	continue;
			//}
			//went[now.tx][now.ty][now.kx][now.ky] = true;


			//test(now, h, w);


			if (now.tx == now.kx && now.ty == now.ky)
			{
				cout << now.tim << endl;

				flg = false;

				break;
			}

			for (i = 0; i < 4; i++)
			{
				//tmp=GoMap(now, i);


				tmp = now;

				if (map[now.ty + gy[i]][now.tx + gx[i]] == 0)
				{
					tmp.ty += gy[i];
					tmp.tx += gx[i];
				}
				if (map[now.ky + gy[i + 4]][now.kx + gx[i + 4]] == 0)
				{
					tmp.ky += gy[i + 4];
					tmp.kx += gx[i + 4];
				}


				if (!ChekNow(tmp))
				{
					tmp.tim++;

					went[tmp.tx][tmp.ty][tmp.kx][tmp.ky] = true;

					nx.push(tmp);
				}
			}
		}

		if (flg)
		{
			cout << "NA\n";
		}

		while (!nx.empty())
		{
			nx.pop();
		}


		memset(went, 0, sizeof(went));
	}
	return 0;
}


bool ChekNow (ST ex)
{
	return went[ex.tx][ex.ty][ex.kx][ex.ky];
}


ST GoMap(ST ex, int i)
{
	if (map[ex.ty + gy[i]][ex.tx + gx[i]] == 0)
	{
		ex.ty += gy[i];
		ex.tx += gx[i];
	}
	if (map[ex.ky + gy[i + 4]][ex.kx + gx[i + 4]] == 0)
	{
		ex.ky += gy[i + 4];
		ex.kx += gx[i + 4];
	}


	return ex;
}