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 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;

const unsigned char INF = 255;
int H,W;
class Point{
public:
  int tx;
  int ty;
  int kx;
  int ky;
  void set(int a,int b,int c,int d){
    tx = a;
    ty = b;
    kx = c;
    ky = d;
  }
};

int is_out_of_area(int y,int x){
  return x < 1 || x > W || y < 1 || y > H;
}
int main(){
  bool F[52][52];
  unsigned char D[52][52][52][52];
  queue<Point> qa;
  Point p;
  int tx,ty,kx,ky;

  while(1){

    cin >> W >> H;
    if(W == 0 && H == 0)
    break;
    cin >> tx >> ty >> kx >> ky;

    for(int y=0;y<=H+1;y++){
      for(int x=0;x<=W+1;x++){
        F[y][x] = 1;
      }
    }
    for(int y=1;y<=H;y++){
      for(int x=1;x<=W;x++){
        int a;
        cin >> a;
        F[y][x] = a;
        for(int i=1;i<=H;i++){
          for(int j=1;j<=W;j++){
            D[y][x][i][j] = INF;
          }
        }
      }
    }
    while(!qa.empty()){
      qa.pop();
    }
    p.set(tx,ty,kx,ky);
    qa.push(p);
    D[p.ty][p.tx][p.ky][p.kx] = 0;
    int counter=0;
    while(1){
      if(qa.empty()){
        cout << "NA" <<endl;
        break;
      }
      p = qa.front();
      qa.pop();
      cout << p.tx << ',' << p.ty << ',' << p.kx << ',' << p.ky << ',' << (int)D[p.ty][p.tx][p.ky][p.kx] << endl;
      if(D[p.ty][p.tx][p.ky][p.kx] >= 100){
        cout << "NA" << endl;
        break;
      }
      if(p.tx == p.kx && p.ty == p.ky){
        cout << (int)D[p.ty][p.tx][p.ky][p.kx] << endl;
        break;
      }
      counter++;
      if(D[p.ty-1][p.tx][p.ky+1][p.kx] == INF){

          int inc_ty = -1 , inc_ky = 1;
          if(is_out_of_area(p.ty-1,p.tx) || F[p.ty-1][p.tx]){
            inc_ty = 0;
          }
          if(is_out_of_area(p.ky+1,p.kx) || F[p.ky+1][p.kx]){
            inc_ky = 0;
          }

          if(inc_ty || inc_ky){
            Point q;
            q.set(p.tx,p.ty + inc_ty,p.kx,p.ky+inc_ky);
            qa.push(q);
            D[p.ty + inc_ty][p.tx][p.ky + inc_ky][p.kx] = D[p.ty][p.tx][p.ky][p.kx] + 1;
          }
      }

      if(D[p.ty+1][p.tx][p.ky-1][p.kx] == INF){

          int inc_ty = 1 , inc_ky = -1;
          if(is_out_of_area(p.ty+1,p.tx) || F[p.ty+1][p.tx]){
            inc_ty = 0;
          }
          if(is_out_of_area(p.ky-1,p.kx) || F[p.ky-1][p.kx]){
            inc_ky = 0;
          }

          if(inc_ty || inc_ky){
            Point q;
            q.set(p.tx,p.ty + inc_ty,p.kx,p.ky+inc_ky);
            qa.push(q);
            D[p.ty + inc_ty][p.tx][p.ky + inc_ky][p.kx] = D[p.ty][p.tx][p.ky][p.kx] + 1;
          }
      }

      if(D[p.ty][p.tx-1][p.ky][p.kx+1] == INF){

          int inc_tx = -1 , inc_kx = 1;
          if(is_out_of_area(p.ty,p.tx + inc_tx) || F[p.ty][p.tx + inc_tx]){
            inc_tx = 0;
          }
          if(is_out_of_area(p.ky,p.kx + inc_kx) || F[p.ky][p.kx + inc_kx]){
            inc_kx = 0;
          }

          if(inc_tx || inc_kx){
            Point q;
            q.set(p.tx + inc_tx,p.ty,p.kx + inc_kx,p.ky);
            qa.push(q);
            D[p.ty][p.tx + inc_tx][p.ky][p.kx + inc_kx] = D[p.ty][p.tx][p.ky][p.kx] + 1;
          }
      }
      if(D[p.ty][p.tx+1][p.ky][p.kx-1] == INF){

          int inc_tx = 1 , inc_kx = -1;
          if(is_out_of_area(p.ty,p.tx + inc_tx) || F[p.ty][p.tx + inc_tx]){
            inc_tx = 0;
          }
          if(is_out_of_area(p.ky,p.kx + inc_kx) || F[p.ky][p.kx + inc_kx]){
            inc_kx = 0;
          }

          if(inc_tx || inc_kx){
            Point q;
            q.set(p.tx + inc_tx,p.ty,p.kx + inc_kx,p.ky);
            qa.push(q);
            D[p.ty][p.tx + inc_tx][p.ky][p.kx + inc_kx] = D[p.ty][p.tx][p.ky][p.kx] + 1;
          }
      }

    }
  }
  return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<queue>
using namespace std;

struct AO
{
	int tx;
	int ty;
	int kx;
	int ky;
	int cnt;
};

queue<AO> Q;
AO TK,f;
int d[52][52];
int sa[51][51][51][51];

int main()
{
	int X,Y,F; //     tx ty kx ky
	int mv[4][4] ={{ 0,-1, 0, 1}, //???
				   { 0, 1, 0,-1}, //???
				   {-1, 0, 1, 0}, //???
				   { 1, 0,-1, 0}};//???
	while(1){
		F = 1;
		for(int i=0;i<52;i++){
			for(int j=0;j<52;j++){
				d[i][j] = 1;
			}
		}
		memset(sa,0,sizeof(sa));
		//printf("%d\n",d[0][0]);
		scanf("%d %d",&X,&Y);
		if(X == 0 && Y == 0) break;
		scanf("%d %d %d %d",&TK.tx,&TK.ty,&TK.kx,&TK.ky);
		sa[TK.ty][TK.tx][TK.ky][TK.kx] = 1;
		TK.cnt = 0;
		Q.push(TK);
		for(int i=1;i<=Y;i++){
			for(int j=1;j<=X;j++){
				scanf("%d",&d[i][j]);
			}
		}

		while(!Q.empty()){    //!Q.empty()
			TK = Q.front();
			Q.pop();
			//printf("?????? ??????:%d %d  ??????:%d %d\n",TK.tx,TK.ty,TK.kx,TK.ky);
			if(TK.cnt >= 100){
				break;
			}
			if(TK.tx == TK.kx && TK.ty == TK.ky){
				F = 0;
				break;
			}
			if(TK.cnt >= 100){
				break;
			}
			for(int i=0;i<4;i++){
				f.tx = TK.tx + mv[i][0];
				f.ty = TK.ty + mv[i][1];
				f.kx = TK.kx + mv[i][2];
				f.ky = TK.ky + mv[i][3];
				f.cnt = TK.cnt + 1;
				//printf("A");
				if(d[f.ty][f.tx] == 0 || d[f.ky][f.kx] == 0){
					if(d[f.ty][f.tx] == 1){
						f.tx = TK.tx;
						f.ty = TK.ty;
					}
					if(d[f.ky][f.kx] == 1){
						f.kx = TK.kx;
						f.ky = TK.ky;
					}
				}
				else if(d[f.ty][f.tx] == 1 && d[f.ky][f.kx] == 1){
					continue;
				}
				if(  sa[f.ty][f.tx][f.ky][f.kx] == 1 || f.tx < 0 || f.kx < 0 || f.ty < 0 || f.ky < 0 || f.tx > X || f.kx > X || f.ty > Y || f.ky > Y){
					continue;
				}
				sa[f.ty][f.tx][f.ky][f.kx] = 1;
				Q.push(f);
				//printf("??????%d %d\n?????? %d %d\n",f.tx,f.ty,f.kx,f.ky);
			}
			//printf("------------\n");
		}
		if(F==0)
			printf("%d\n",TK.cnt);
			//printf("%d %d %d %d\n",TK.tx,TK.ty,TK.kx,TK.ky);
		else
			printf("NA\n");
		while(!Q.empty())
			Q.pop();
	}
	return 0;
}