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<queue>
#include<iostream>
#include<algorithm>
using namespace std;
struct maigo{
	int x[2];// ????????????[0]???????????????[1]
	int y[2];// ????????????[0]???????????????[1]
	int count;
};
int x1[1000000] = { 0 };
int x2[1000000] = { 0 };
int y3[1000000] = { 0 };
int y2[1000000] = { 0 };
int main(){
	queue<maigo> q;
	int tx, ty; int kx, ky;
	int **depart, X, Y;
	int flag = 0, a = 0;
	int c = 0;
	int f = 0;
	cin >> X >> Y;
	while (X != 0 && Y != 0){
		depart = new int*[Y + 2];
		for (int i = 0; i < Y + 2; i++){
			depart[i] = new int[X + 2];
		}
		for (int i = 0; i < Y + 2; i++){
			for (int l = 0; l < X + 2; l++){
				depart[i][l] = 3;
			}
		}
		cin >> tx >> ty;
		cin >> kx >> ky;
		for (int i = 1; i < Y + 1; i++){
			for (int l = 1; l < X + 1; l++){
				cin >> depart[i][l];
			}
		}
		maigo temp;
		temp.x[0] = tx; temp.y[0] = ty;
		temp.x[1] = kx; temp.y[1] = ky;
		temp.count = 1;
		q.push(temp);
		while (!q.empty() && flag == 0){
			maigo t = q.front();
			maigo into;
			q.pop();
			if (t.count >= 100){
				a = 1; flag = 1; 
				break;
			}
			int dx1[4] = { 1, 0, -1, 0 }; int dx2[4] = { 0, 1, 0, -1 };
			for (int i = 0; i < 4; i++){
				for (int l = 0; l <= c; l++){
					if (x1[l] == t.x[0] + dx1[i] && y3[l] == t.y[0] + dx2[i] &&
						x2[l] == t.x[1] + dx1[i] * (-1) && y2[l] == t.y[1] + dx2[i] * (-1)) f = 1;
				}if (f == 0){
					x1[c] = t.x[0] + dx1[i];
					y3[c] = t.y[0] + dx2[i];
					x2[c] = t.x[1] + dx1[i] * (-1);
					y2[c] = t.y[1] + dx2[i] * (-1);
					c++;
				}
				else if (f == 1){
					f = 0;
					break;
				}
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 &&
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					if (t.x[0] + dx1[i] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] + dx2[i] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);
					into.count = t.count + 1;
					q.push(into);
				}
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 && //???????????? ok ???????????? no ?????´???
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] != 0){
					if (t.x[0] + dx1[i] == t.x[1] &&
						t.y[0] + dx2[i] == t.y[1]){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1], into.y[1] = t.y[1];
					into.count = t.count + 1;
					q.push(into);
				}
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] != 0 && //???????????? no??????????????? yes????????´???
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					if (t.x[0] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0], into.y[0] = t.y[0];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);
					into.count = t.count + 1;
					q.push(into);
				}
			}
		}if (a == 1||flag == 0) {
			cout << "NA" << endl;
		}while (!q.empty()) q.pop();
		a = 0; flag = 0;
		cin >> X >> Y;
	}
	return 0;
}

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

class pos{
 public:
  int x1;
  int y1;
  int x2;
  int y2;
  pos(int xa1,int ya1,int xa2,int ya2){
    x1=xa1;
    y1=ya1;
    x2=xa2;
    y2=ya2;
  }
  bool eq(){
    return x1==x2&&y1==y2;
  }
};

char map[52][52];

int main(){
  int i,j,x,y,tx,ty,kx,ky,b,dir[][2]={{1,0},{-1,0},{0,1},{0,-1}};
  using namespace std;
  list<pos> mlst,add,now;
  list<pos>::iterator it,se;
  pos *nx;
  for(i=0;i<52;i++) map[i][0]=map[0][i]=1;
  do{
    scanf("%d %d",&x,&y);
    if(!x&&!y) break;
    mlst.clear();
    now.clear();
    scanf("%d %d",&tx,&ty);
    scanf("%d %d",&kx,&ky);
    if(tx==kx&&ky==ty){
      printf("0\n");
      goto meet;
    }
    nx=new pos(tx,ty,kx,ky);
    mlst.push_back(*nx);
    now.push_back(*nx);
    for(i=0;i<y;i++){
      for(j=0;j<x-1;j++){
	scanf("%d ",&b);
	map[i+1][j+1]=b;
      }
      scanf("%d",&b);
      map[i+1][j+1]=b;
      map[i+1][j+2]=1;
    }
    for(i=1;i<x+2;i++) map[y+1][i]=1;
    for(i=1;i<100;i++){
      it=now.begin();
      while(it!=now.end()){
	for(j=0;j<4;j++){
	  if(map[it->y1+dir[j][0]][it->x1+dir[j][1]]){
	    tx=it->x1;
	    ty=it->y1;
	  }else{
	    tx=it->x1+dir[j][1];
	    ty=it->y1+dir[j][0];
	  }
	  if(map[it->y2+-1*dir[j][0]][it->x2+-1*dir[j][1]]){
	    kx=it->x2;
	    ky=it->y2;
	  }else{
	    kx=it->x2+-1*dir[j][1];
	    ky=it->y2+-1*dir[j][0];
	  }
	  se=add.begin();
	  while(se!=add.end()){
	    if(se->x1==tx&&se->y1==ty&&
	       se->x2==kx&&se->y2==ky) goto cont;
	    se++;
	  }
	  se=mlst.begin();
	  while(se!=mlst.end()){
	    if(se->x1==tx&&se->y1==ty&&
	       se->x2==kx&&se->y2==ky) goto cont;
	    se++;
	  } 
	  nx=new pos(tx,ty,kx,ky);
	  if(nx->eq()){
	    printf("%d\n",i);
	    add.clear();
	    goto meet;
	  }
	  add.push_back(*nx);
	cont:;
	}
	it++;
      }
      if(add.empty()){
	printf("NA\n");
	goto meet;
      }
      now.clear();
      now.insert(now.end(),add.begin(),add.end());
      mlst.insert(mlst.end(),add.begin(),add.end());
      add.clear();
    }
    printf("NA\n");
  meet:;
  }while(1);
  return 0;
}