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<iostream>
#include<queue>
#include<map>
#include<cstring>
using namespace std;

struct node 
{
  int step;
  int tx,ty;
  int kx,ky;
  node(int s,int ttx,int tty,int kkx,int kky):
    step(s),tx(ttx),ty(tty),kx(kkx),ky(kky){} 
};
  
int main()
{
  int x,y;
  for(;cin>>x>>y,x;)
    {
      bool data[52][52];
      int tx,ty,kx,ky;
      cin>>tx>>ty>>kx>>ky;
      memset(data,false,sizeof(data));
      for(int i=1;i<=x;i++)
	for(int j=1;j<=y;j++)
	  {
	    char tmp;
	    cin>>tmp;
	    data[j][i]=(tmp=='0');
	  }
      queue<node> qu;
      qu.push(node(0,tx,ty,kx,ky));
      map< pair<pair<int,int>,pair<int,int> > ,bool >hash;      
      int ans=-1;
      int dx[]={0,0,1,-1};
      int dy[]={1,-1,0,0};
      while(!qu.empty())
	{
	  node tmp=qu.front();
	  qu.pop();
	  //	  cout<<tmp.step<<" "<<tmp.tx<<" "<<tmp.ty<<" "<<tmp.kx<<" "<<tmp.ky<<endl;
	  if(hash[make_pair(make_pair(tmp.tx,tmp.ty),make_pair(tmp.kx,tmp.ky))])
	    continue;
	  if(tmp.tx==tmp.kx &&tmp.ty==tmp.ky)
	    {
	      ans=tmp.step;
	      break;
	    }
	  if(tmp.step>99)
	    continue;
	  hash[make_pair(make_pair(tmp.tx,tmp.ty),make_pair(tmp.kx,tmp.ky))]=true;
	  for(int i=0;i<4;i++)
	    {
	      int ttx=tmp.tx,tty=tmp.ty,tkx=tmp.kx,tky=tmp.ky;
	      if(data[ttx+dx[i]][tty+dy[i]])
		{
		  ttx+=dx[i];
		  tty+=dy[i];
		}
	      if(data[tkx-dx[i]][tky-dy[i]])
		{
		  tkx-=dx[i];
		  tky-=dy[i];
		}
	      //cout<<"make"<<ttx<<" "<<tkx<<" "<<tty<<" "<<tty<<endl;	      
	      if(!hash[make_pair(make_pair(ttx,tty),make_pair(tkx,tky))])
		qu.push(node(tmp.step+1,ttx,tty,tkx,tky));
	    }
	}
      if(ans==-1)
	cout<<"NA"<<endl;
      else
	cout<<ans<<endl;

    }
}

C++: #include<queue>
#include<stdio.h>

using namespace std;

class T{
	public:
	int x1,x2,y1,y2,count;
	T(int x1,int y1,int x2,int y2,int count):x1(x1),y1(y1),x2(x2),y2(y2),count(count){}
};

char check[55][55][55][55];
int board[55][55];

int main(){
	while(1){
		for(int i=0;i<55;i++){
			for(int j=0;j<55;j++){
				for(int k=0;k<55;k++){
					for(int p=0;p<55;p++){
						check[i][j][k][p]=0;
					}
				}
			}
		}
		
		int w,h;
		int sx1,sx2,sy1,sy2;
		
		scanf("%d%d",&w,&h);
		if(w==0 && h==0)break;
		
		scanf("%d%d%d%d",&sx1,&sy1,&sx2,&sy2);
		
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				scanf("%d",&board[i][j]);
			}
		}
		
		
		queue<T> que;
		que.push(T(sx1,sy1,sx2,sy2,0));
		
		while(1){
			if(que.empty())break;
			
			T u = que.front();
			que.pop();
			
			if(check[u.x1][u.y1][u.x2][u.y2]==1)continue;
			check[u.x1][u.y1][u.x2][u.y2]=1;
			
			if(u.count>=100)break;
			if(u.x1 == u.x2 && u.y1 == u.y2){
				printf("%d\n",u.count);
				goto A;
			}
			
			int dx[4] = {0,1,0,-1};
			int dy[4] = {1,0,-1,0};
			for(int i=0;i<4;i++){
				int nx1 = u.x1 + dx[i];
				int ny1 = u.y1 + dy[i];
				
				int nx2 = u.x2 - dx[i];
				int ny2 = u.y2 - dy[i];
				
				if(nx1<0 || ny1<0 || nx1>=w || ny1>=h || board[ny1][nx1]==1){
					nx1=u.x1;
					ny1=u.y1;
					continue;
				}
				if(nx2<0 || ny2<0 || nx2>=w || ny2>=h || board[ny2][nx2]==1){
					nx2=u.x2;
					ny2=u.y2;
					continue;
				}
				que.push(T(nx1,ny1,nx2,ny2,u.count+1));
			}
		}
		
		printf("NA\n");
		A:;
	}
}

C++: #include <iostream>
#include <queue>
#include <map>
#include <string>


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

int X, Y;

bool map[50][50];
bool passed[50][50][50][50];

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

    P(int _tx, int _ty, int _kx, int _ky, int _cost) : tx(_tx), ty(_ty), kx(_kx), ky(_ky), cost(_cost) {};
};

bool check(int x, int y)
{
    return x < 0 || x >= X || y < 0 || y >= Y || map[y][x];
}

int main()
{
    int tx, ty, kx, ky, ans;
    while(cin >> X >> Y, X|Y)
    {
        ans = -1;
        memset(passed, 0, sizeof passed);
        queue<P> que;

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

        for(int i = 0; i < Y; i++)
            for(int j = 0; j < X; j++)
                cin >> map[i][j];

        passed[tx][ty][kx][ky] = true;

        for(que.push(P(tx, ty, kx, ky, 0)); !que.empty(); que.pop())
        {
            P p = que.front();

            if(p.cost >= 100)
                break;

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

            for(int i = 0; i < 4; i++)
            {
                int mtx = p.tx + dx[0][i], mty = p.ty + dy[0][i];
                int mkx = p.kx + dx[1][i], mky = p.ky + dy[1][i];

                if(check(mtx, mty))
                    mtx = p.tx, mty = p.ty;
                if(check(mkx, mky))
                    mkx = p.kx, mky = p.ky;
                if(passed[mtx][mty][mkx][mky])
                    continue;

                passed[mtx][mty][mkx][mky] = true;
                que.push(P(mtx, mty, mkx, mky, p.cost + 1));
            }
        }

        if(ans == -1)
            puts("NA");
        else
            cout << ans << endl;
    }
}