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>
using namespace std;

const unsigned char INF = 255;
int H,W;
  bool F[52][52];
  unsigned char D[52][52][52][52];

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(){

  queue<Point> qa;
  Point p;
  int a,tx,ty,kx,ky;
  int inc_ty,inc_ky,inc_ky,inc_kx;
  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++){
        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;
          }
        }
      }
    }

    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){

           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){

          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){

          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){

           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;
          }
      }

    }
    while(!qa.empty()){
      qa.pop();
    }
  }
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<queue>
#include<map>
#include<algorithm>
#include<cstring>
#include<string.h>
using namespace std;
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) {};
};
int hx,hy,rx,ry;
int X,Y;
int mas[110][110],d[51][51][51][51];
int dx[4] = {0,1,0,-1},dy[4] = {1,0,-1,0};
int bfs();
int main(){
  while(1){
  scanf("%d %d",&X,&Y);
  if(X == 0 && Y == 0)break;
  scanf("%d %d",&hx,&hy);
  scanf("%d %d",&rx,&ry);
  for(int i = 1; i <= Y; i++){
    for(int j = 1; j <= X; j++){
      scanf("%d",&mas[i][j]);
    }
  }
  int ans = bfs();
  if(ans == -1)cout << "NA" << endl;
  else cout << ans << endl;
  }
}
int bfs(){
  queue<P> que;
  memset(d,-1,sizeof(d));
  que.push(P(hx,hy,rx,ry,0));
  d[hx][hy][rx][ry] = 0;
  while(!que.empty()){
    P p = que.front();
    que.pop();
    if(p.cost >= 100)return -1;
    if(p.tx == p.kx && p.ty == p.ky){
      return p.cost;
    }
    for(int i = 0; i < 4; i++){
      int nx = p.tx + dx[i], ny = p.ty + dy[i];
      int ux = p.kx - dx[i], uy = p.ky - dy[i];
      if(nx > 0 && ny > 0 && ux > 0 && uy > 0 && nx <= X && ny <= Y && ux <= X && uy <= Y && mas[ny][nx] != 1 && mas[uy][ux] != 1 && d[nx][ny][ux][uy] == -1){
	que.push(P(nx,ny,ux,uy,p.cost++));
	d[nx][ny][ux][uy] =  1;
      }
      else if((nx <= 0 || nx > X || ny <= 0 || ny > Y || mas[ny][nx] == 1) && ux <= X && uy <= Y && ux > 0 && uy > 0 && mas[uy][ux] != 1 && d[nx][ny][ux][uy] == -1){
	que.push(P(p.tx,p.ty,ux,uy,p.cost++));
	d[p.tx][p.ty][ux][uy] = 1;
      }
      else if((ux <= 0 || ux > X || uy <= 0 || uy > Y || mas[uy][ux] == 1) && nx <= X && ny <= Y && nx > 0 && ny > 0 && mas[ny][nx] != 1 && d[nx][ny][ux][uy] == -1){
	que.push(P(nx,ny,p.kx,p.ky,p.cost++));
	d[nx][ny][p.kx][p.ky] = 1;
      }
    }
  }
  return -1;
}