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 := 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]
			}
			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>
using namespace std;

bool isnot_table[51][51][51][51];

const int rightmove = 1;
const int leftmove = -1;
const int up = -1;
const int down = 1;

struct Point{
  int x;
  int y;
};

struct DoublePoint{
  Point m;
  Point l;
  int count;
};

int main(){

    while(1){

      int w,h;

      cin >> w >> h;

      if(w==0 && h==0)
        break;

      int table[w+1][h+1];

      DoublePoint bro;

      cin >> bro.m.x >> bro.m.y >> bro.l.x >> bro.l.y;

      bro.count = 0;

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

  /*    for(int i=1;i<w+1;i++){
        for(int j=1;j<h+1;j++){
          cout << table[i][j] << " ";
        }
        cout << endl;
      }*/

      if(bro.m.x == bro.l.x && bro.l.x == bro.l.y){
        cout << 0 << endl;
        continue;
      }


      for(int i=1;i<=w;i++){
        for(int j=1;j<=h;j++){

          if(table[i][j]==0){
            for(int k=1;k<=w;k++){
              for(int p=1;p<=h;p++){

                if(table[k][p]==0){
                  //cout << i << " " << j << " " << k << " " << p << endl;
                  isnot_table[i][j][k][p] = true;
                }
                else{
                  isnot_table[i][j][k][p] = false;
                }

              }
            }
          }
          else{
            for(int k=1;k<=w;k++){
              for(int p=1;p<=h;p++){
                isnot_table[i][j][k][p] = false;
              }
            }
          }

        }
      }

      isnot_table[bro.m.x][bro.m.y][bro.l.x][bro.l.y] = false;

      queue<DoublePoint> q;

      q.push(bro);

      while(!q.empty()){

        DoublePoint BefroreTwin = q.front();

        q.pop();

        BefroreTwin.count++;

        if(BefroreTwin.count >= 100){
          cout << "NA" << endl;
          q.push(BefroreTwin);
          break;
        }

        DoublePoint tmp = BefroreTwin;




        if(table[tmp.m.x+leftmove][tmp.m.y]==0 && tmp.m.x != 1){
          tmp.m.x += leftmove;
        }
        if(table[tmp.l.x+rightmove][tmp.l.y]==0 && tmp.l.x != w){
          tmp.l.x += rightmove;
        }

        //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
               //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
          if(tmp.m.x == tmp.l.x && tmp.m.y == tmp.l.y){
            cout << tmp.count << endl;
            q.push(tmp);//cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }
        tmp = BefroreTwin;


        if(table[tmp.m.x+rightmove][tmp.m.y]==0 && tmp.m.x != w){
          tmp.m.x += rightmove;
        }
        if(table[tmp.l.x+leftmove][tmp.l.y]==0 && tmp.l.x != 1){
          tmp.l.x += leftmove;
        }       // cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
               //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
          if(tmp.m.x == tmp.l.x && tmp.m.y == tmp.l.y){
            cout << tmp.count << endl;
            q.push(tmp);//cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);

        }

        tmp = BefroreTwin;


        if(table[tmp.m.x][tmp.m.y+up]==0 && tmp.m.y != 1){
          tmp.m.y += up;
        }
        if(table[tmp.l.x][tmp.l.y+down]==0 && tmp.l.y != h){
          tmp.l.y += down;
        }        //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
               //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
          if(tmp.m.x == tmp.l.x && tmp.m.y == tmp.l.y){
            cout << tmp.count << endl;
            q.push(tmp);//cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }

        tmp = BefroreTwin;


        if(table[tmp.m.x][tmp.m.y+down]==0 && tmp.m.y != h){
          //cout << "a ";
          tmp.m.y += down;
        }
        if(table[tmp.l.x][tmp.l.y+up]==0 && tmp.l.y != 1){
          //cout << "b ";
          tmp.l.y += up;
        }
          //cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
               //cout << 1  << "  " << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
          if(tmp.m.x == tmp.l.x && tmp.m.y == tmp.l.y){
            cout << tmp.count << endl;
            q.push(tmp);//cout << tmp.m.x << " " << tmp.m.y << " " << tmp.l.x << " " << tmp.l.y << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }

      }

      if(q.empty()){
        cout << "NA" << endl;
      }

    }
    return 0;
}