Go: package main

import (
	"container/heap"
	"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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

func solve(h, w int64) {
	var tx, ty, kx, ky int64
	fmt.Scan(&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)
	heap.Init(&pq)
	heap.Push(&pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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 += 1
			if next.Turn < 100 {
				heap.Push(&pq, next)
			}
		}
	}
	fmt.Println("NA")
}

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<algorithm>
using namespace std;
 
typedef pair<int,int> PA;
typedef pair<PA,PA> PPA;
 
int dx[] = {1,-1,0,0};
int dy[] = {0,0,1,-1};
 
int masu[55][55][55][55]; 

int main(){
  
  int w,h,tx,ty,kx,ky,ans;
  int d[55][55];
  
  while(cin >> w >> h,w!=0&&h!=0){
    cin >> tx >> ty >> kx >> ky;
    tx--;
    ty--;
    kx--;
    ky--;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	cin >> d[i][j];
      }
    }
    
    ans = 101;
    
    queue<PPA> que;
    
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	for(int k=0;k<h;k++){
	  for(int l=0;l<w;l++) masu[i][j][k][l] = -1;
	}
      }
    }
    masu[ty][tx][ky][kx] = 0;
    que.push(PPA(PA(ty,tx),PA(ky,kx)));
    
    while(!que.empty()){
      PPA p = que.front();
      que.pop();
      
      int y1 = p.first.first;
      int x1 = p.first.second;
      int y2 = p.second.first;
      int x2 = p.second.second;
      
      for(int i=0;i<4;i++){
	int ay = y1 + dy[i];
	int ax = x1 + dx[i];
	if(ay<0||ay>=h||ax<0||ax>=w||d[ay][ax] == 1){
	  ay = y1;
	  ax = x1;
	}
	int by = y2 - dy[i];
	int bx = x2 - dx[i];
	if(by<0||by>=h||bx<0||bx>=w||d[by][bx] == 1){
	  by = y2;
	  bx = x2;
	}
	if(masu[ay][ax][by][bx]!=-1) continue;
	masu[ay][ax][by][bx] = masu[y1][x1][y2][x2]+1;
	
	if(masu[ay][ax][by][bx] >= 100) continue;
	que.push(PPA(PA(ay,ax),PA(by,bx)));
	
	if(ay==by&&ax==bx) ans = min(ans,masu[ay][ax][by][bx]);
	
      }
    }
    
    if(ans >= 100) cout << "NA" << endl;
    else cout << ans << endl;
    
  }
  return(0);
}

C++: #include<iostream>
#include<queue>

using namespace std;
#define MAX 64

typedef pair<int,int> pi;

const int di[] = {-1,0,1,0};
const int dj[] = {0,1,0,-1};


bool isinside(pi pos, int H, int W){
  return 0<=pos.first&&pos.first<H&&0<=pos.second&&pos.second<W;
}
class State{
public:
  pi taka;
  pi kazu;
  int time;
  State( pi taka, pi kazu, int t ):taka(taka),kazu(kazu),time(t){}
};

int bfs(int sti, int stj, int ski, int skj, int H, int W, bool M[][MAX]){
  static bool vis[50][50][50][50];
  for(int i = 0; i < H; ++i){
    for(int j = 0; j < W; ++j){
      for(int k = 0; k < H; ++k){
	for(int l = 0; l < W; ++l){
	  vis[i][j][k][l] = false;
	}
      }
    }
  }

  State st(pi(sti,stj),pi(ski,skj),0);
  queue<State> qs;
  qs.push( st );
  while(!qs.empty()){
    State now = qs.front();
    qs.pop();
    //cout << now.taka.first << ' ' << now.taka.second << ' ' << now.kazu.first << ' ' << now.kazu.second << endl;
    if( now.taka.first == now.kazu.first && now.taka.second == now.kazu.second ){
      return now.time;
    }
    for(int k = 0; k < 4; ++k){
      pi ntaka( now.taka.first+di[k], now.taka.second+dj[k] );
      pi nkazu( now.kazu.first+di[(k+2)%4], now.kazu.second+dj[(k+2)%4]);
      if( !isinside(ntaka,H,W ) ){
	ntaka = now.taka;
      }else{
	if( M[ntaka.first][ntaka.second] )
	  ntaka = now.taka;
      }

      if( !isinside(nkazu,H,W ) ){
	nkazu = now.kazu;
      }else{
	if( M[nkazu.first][nkazu.second] )
	  nkazu = now.kazu;
      }

      if( !vis[ntaka.first][ntaka.second][nkazu.first][nkazu.second] ){
	vis[ntaka.first][ntaka.second][nkazu.first][nkazu.second] = true;
      
	State next( ntaka, nkazu, now.time+1 );
	qs.push( next );
      }
    }
  }
  return -1;
}

int main()
{
  while(true){
    int H, W;
    
    cin >> H >> W;
    if( H == 0 && W == 0 ) break;
    bool m[MAX][MAX];
    int tx,ty;
    int kx,ky;  
    cin >> tx >> ty;
    cin >> kx >> ky;
    --tx;--ty;--kx;--ky;
    for(int i = 0; i < H; ++i){
      for(int j = 0; j < W; ++j){
	cin >> m[i][j];
      }
    }
    int ans = bfs( ty, tx, ky, kx, H, W, m);
    if( ans < 0 ){
      cout << "NA" << endl;
    }
    else{
      cout << ans << endl;
    }
  }
  return 0;
}