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>
#include <cstring>
using namespace std;


int H,W;
bool F[52][52]; //障害物
bool D[52][52][52][52]; //探索済みかの判定用
int inc_tx[4] = {1,-1,0,0};
int inc_ty[4] = {0,0,1,-1};
int inc_kx[4] = {-1,1,0,0};
int inc_ky[4] = {0,0,-1,1};

class Point{
public:
  int tx; //タカユキの座標
  int ty;
  int kx; //カズユキの座標
  int ky;
  int d; //ターン回数
  void set(int a,int b,int c,int d){
    tx = a;
    ty = b;
    kx = c;
    ky = d;
  }
};

bool is_out_of_area(int y,int x) //座標が範囲内か確認する関数
{
  return x < 1 || x > W || y < 1 || y > H || F[y][x];
}

int main(){

  while(1){

    Point p,q;
    int tx,ty,kx,ky;
    queue<Point> qa;
    cin >> W >> H;
    if(W == 0 && H == 0)
    break;
    cin >> tx >> ty >> kx >> ky;
    memset(F,1,sizeof(F));
    for(int y=1;y<=H;y++){
      for(int x=1;x<=W;x++){
        cin >> F[y][x];
      }
    }
    memset(D,1,sizeof(D));
    p.set(tx,ty,kx,ky);
    D[ty][tx][ky][kx] = 0;
    p.d = 0;
    qa.push(p);
    while(1){
      if(qa.empty()){
        cout << "NA" <<endl;
        break;
      }
      p = qa.front();
      qa.pop();
      if(p.d >= 100){
        cout << "NA" << endl;
        break;
      }
      if(p.tx == p.kx && p.ty == p.ky){
        cout << p.d << endl;
        break;
      }
      for(int i=0;i<4;i++){
        q.tx = p.tx + inc_tx[i]; q.ty = p.ty + inc_ty[i];
        q.kx = p.kx + inc_kx[i]; q.ky = p.ky + inc_ky[i];
        if(D[q.ty][q.tx][q.ky][q.kx]){
          if(is_out_of_area(q.ty ,q.tx) == 0 || is_out_of_area(q.ky ,q.kx) == 0){
            if(is_out_of_area(q.ty ,q.tx)){
              q.ty = p.ty; q.tx = p.tx;
            }
            if(is_out_of_area(q.ky ,q.kx)){
              q.ky = p.ky; q.kx = p.kx;
            }
            q.d = p.d + 1;
            qa.push(q);
            D[q.ty][q.tx][q.ky][q.kx] = 0;
          }
        }
      }
    }
  }
  return 0;
}

C++: #include<complex>
#include<algorithm>
#include<iostream>
#include<iomanip>
#include<cmath>
#include<vector>
#include<map>
#include<sstream>
#include<ctime>
#include<cstdio>
#include<cstdlib>
#include<cassert>
#include<deque>
#include<queue>
#include<climits>
#include<list>
#include<stack>
#include<ctime>
#define all(n) n.begin(),n.end()
#define REP(i,s,n) for(int i=s;i<n;i++)
#define rep(i,n) REP(i,0,n)
#define PPPinsert(a,b,c,d,e,f) PPP(PP(P(a,b),P(c,d)),P(e,f))
#define F first
#define S second
#define pb push_back
#define INF (1<<27)
#define EPS 1e-10
#define equals(a,b) (fabs((a)-(b)) < EPS)

using namespace std;
typedef pair<int,int> P;
typedef pair<P,P> PP;
typedef pair<PP,P> PPP;
typedef unsigned long long ull;
typedef long long ll;
const int dx[4] = {0,1,0,-1};
const int dy[4] = {1,0,-1,0};

int rdir(int i){
  switch(i){
  case 0:
    return 2;
  case 1:
    return 3;
  case 2:
    return 0;
  case 3: 
    return 1;
  default:
    return -1; 
  }
}

class Pox{
private:
  PPP element;
public:

  Pox(){}
  Pox(PPP element):element(element){}

  PPP get(){
    return element;
  }  

  void print(){
    cout << "takayuki " << element.F.F.F << "," << element.F.F.S << " : kazuyuki " << element.F.S.F << " : " << element.F.S.S << " : cost " << element.S.F << " : distance " << element.S.S << endl;   
  }

};

struct Comparator_X{
  bool operator() (Pox &a,Pox &b){
    if(a.get().S.F != a.get().S.F)return a.get().S.F < b.get().S.F;
    return a.get().S.S < b.get().S.S;
  }
};

int main(){
  int h,w;
  while(true)
    {
      cin >> w >> h;
      if(w+h == 0)break;
      P takayuki,kazuyuki;
      cin >> takayuki.F >> takayuki.S;
      cin >> kazuyuki.F >> kazuyuki.S;

      PPP first_element;//PPP(PP(P(takayuki-x,takayuki-y),P(kazuyuki-x,kazuyuki-y)),P(cost,distance))
      first_element = PPPinsert(takayuki.F,takayuki.S,kazuyuki.F,kazuyuki.S,0,abs(takayuki.F-kazuyuki.F)+abs(takayuki.S-kazuyuki.S));


      bool bmap[h][w];
      bool used_t[h][w],used_h[h][w];
      rep(i,h)
	{
	  rep(j,w)
	    {
	      cin >> bmap[i][j];
	      used_t[i][j] = false,used_h[i][j] = false;     
	    }
	}

      used_t[takayuki.S][takayuki.F] = used_h[kazuyuki.S][kazuyuki.F] = true;

      priority_queue<Pox,vector<Pox>,Comparator_X> pq;
      pq.push(first_element);

      bool fin = false;

      while(!pq.empty())
	{
	  Pox pox = pq.top(); pq.pop();
	  
	  for(int i=0;i<4;i++)
	    {
	      int t_nx,t_ny,h_nx,h_ny;
	      t_nx = pox.get().F.F.F + dx[i],t_ny = pox.get().F.F.S + dy[i];
	      h_nx = pox.get().F.S.F + dx[rdir(i)],h_ny = pox.get().F.S.S + dy[rdir(i)];

	      if(used_t[t_ny][t_ny] && used_h[h_ny][h_nx])
		continue;	      

	      if(!(0<= t_nx && t_nx < w && 0<= t_ny && t_ny < h) || bmap[t_ny][t_nx])
		continue;

	      if(!(0<= h_nx && h_nx < w && 0<= h_ny && h_ny < h) || bmap[h_ny][h_nx])
		continue;

	      if(t_nx == h_nx && t_ny == h_ny)
		{
		  cout << pox.get().S.F+1 << endl;
		  fin = true;
		  break;
		}

	      used_h[h_ny][h_nx] = used_t[t_ny][t_nx] = true;
	      Pox inpox = Pox(PPPinsert(t_nx,t_ny,h_nx,h_ny,pox.get().S.F+1,abs(t_nx-h_nx)+abs(t_ny-h_ny)));
	      pq.push(inpox);
	    }

	}      

      if(!fin)
        cout << "NA" << endl;
	

      
    }
  return 0;
}