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>
using namespace std;

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

int main(){
  while(true){
      int X, Y;
      cin >> X >> Y;
      if(X==0&&Y==0)
          break;

      int d[52][52];
      for(int y=0; y<=Y+1; y++)
          for(int x=0; x<=X+1; x++)
                d[y][x] = 1;

      struct point now;
      cin >> now.tx >> now.ty;
      cin >> now.kx >> now.ky;
      now.t = 0;

      queue<struct point> que;
      que.push(now);

      map<int, bool> org;

      for(int y=1; y<=Y; y++)
          for(int x=1; x<=X; x++)
                cin >> d[y][x];

      while(true){
          if(que.empty()){
              cout << "NA" << endl;
                break;
          }

          now = que.front();
          que.pop();

          int tk = ((now.tx*100+now.ty)*100+now.kx)*100+now.ky;
          if(org.find(tk)!=org.end())
              continue;
          else
              org[tk] = true;

          if(now.t>=100){
              cout << "NA" << endl;
              break;
          }

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

          struct point nxt = now;
          if(d[nxt.ty-1][nxt.tx]==0)
              nxt.ty--;
          if(d[nxt.ky+1][nxt.kx]==0)
              nxt.ky++;
          nxt.t++;
          que.push(nxt);

          nxt = now;
          if(d[nxt.ty+1][nxt.tx]==0)
              nxt.ty++;
          if(d[nxt.ky-1][nxt.kx]==0)
              nxt.ky--;
          nxt.t++;
          que.push(nxt);

          nxt = now;
          if(d[nxt.ty][nxt.tx-1]==0)
              nxt.tx--;
          if(d[nxt.ky][nxt.kx+1]==0)
              nxt.kx++;
          nxt.t++;
          que.push(nxt);

          nxt = now;
          if(d[nxt.ty][nxt.tx+1]==0)
              nxt.tx++;
          if(d[nxt.ky][nxt.kx-1]==0)
              nxt.kx--;
          nxt.t++;
          que.push(nxt);
      }
  }

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

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

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

    for(int i=0;i<4;i++){

      int f=0;
      
      if(p.co+1>=100) continue;
      
      if(kx+dx[i]*-1 <= 0 || ky+dy[i]*-1 <=0 || kx+dx[i]*-1 > X || ky+dy[i]*-1 > Y)
	f+=10;      
      if(tx+dx[i] <= 0 || ty+dy[i] <= 0 || tx+dx[i] > X || ty+dy[i] > Y )
	f++;

      if( xy[ty+dy[i]][tx+dx[i]]==1 )
	f++;
      if(xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	f+=10;

      if(f/10>0 && f%10>0)
	continue;


      if(f==0){
	if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1)
	  return p.co+1;
	if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] <= p.co)
	  continue;
	q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );
      }
      else if(f%10>0){
	if(tx == kx+dx[i]*-1 && ty == ky+dy[i]*-1)
	  return p.co+1;
	if( cost[tx][ty][kx+dx[i]*-1][ky+dy[i]*-1] <= p.co)
	  continue;
	q.push( state(tx,ty,kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );
      }
      else if(f/10>0){
	if(tx+dx[i] == kx && ty+dy[i] == ky)
	  return p.co+1;
	if( cost[tx+dx[i]][ty+dy[i]][kx][ky] <= p.co)
	  continue;
	q.push( state(tx+dx[i],ty+dy[i],kx,ky,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=1;i<=Y;i++){
      for(j=1;j<=X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx,ty,kx,ky);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}