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<cstring>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
using namespace std;
struct P{
  P(){};
  P(int a,int b){
    x=a,y=b;
  }
  int x,y;
  void move(int,int);
};
struct S{
  S(){};
  S(P a,P b){
    t=a;
    k=b;
  }
  P t,k;
  void move(int);
};
 
P size;
S f_pos;
vector<vector<int> > f;
bool input(){
  size=P();
  f_pos=S();
  f.clear();
  cin>>size.y>>size.x;
  if(size.x==0&&size.y==0)return false;
  cin>>f_pos.t.y>>f_pos.t.x;
  cin>>f_pos.k.y>>f_pos.k.x;
  vector<int> t;
  for(int i=0;i<size.y+2;i++){
    t.push_back(1);
  }
  f.push_back(t);
  for(int i=0;i<size.x;i++){
    vector<int> tt;
    tt.push_back(1);
    for(int j=0;j<size.y;j++){
      int tmp;
      cin>>tmp;
      tt.push_back(tmp);
    }
    tt.push_back(1);
    f.push_back(tt);
  }
  f.push_back(t);
  return true;
}
int cost[60][60][60][60];
const int vx[]={0,0,1,-1};
const int vy[]={1,-1,0,0};
void S::move(int i){
  t.move(vx[i],vy[i]);
  k.move(-vx[i],-vy[i]);
}
void P::move(int a,int b){
  if(f[x+a][y+b]!=1){
    x+=a;
    y+=b;
  }
}
int solve(){
  memset(cost,-1,(60*60*60*60));
  queue<S> q;
  q.push(f_pos);
  cost[f_pos.t.x][f_pos.t.y][f_pos.k.x][f_pos.k.y]=0;
  while(!q.empty()){
    S now = q.front();q.pop();
    for(int i=0;i<4;i++){
      S tmp = now;
      tmp.move(i);
      if(cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y]!=-1)continue;
 
      cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y] = cost[now.t.x][now.t.y][now.k.x][now.k.y]+1;
      if(cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y]>=100){
        return -1;
      }else if( (tmp.t.x==tmp.k.x)&&(tmp.t.y==tmp.k.y) ){
        return cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y];
      }else{
        q.push(tmp);
      }
    }
  }
  return -1;
}
int main(){
  while(input()){
    /*
    for(int i=0;i<f.size();i++){
      for(int j=0;j<f[i].size();j++){
        cout<<f[i][j];
      }cout<<endl;
    }cout<<endl;
    */
    int ans= solve();
    if(ans==-1||ans>=100){
      cout<<"NA"<<endl;
    }else{
      cout<<ans<<endl;
    }
  }
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef struct{
  int c;
  int tx;
  int ty;
  int kx;
  int ky;
} Data;


short memo[50][50][50][50] = {};

int ido1[4] = {0,0,1,-1};
int ido2[4] = {1,-1,0,0};
int ido3[4] = {0,0,-1,1};
int ido4[4] = {-1,1,0,0};

int main(){
  int w,h;
  int cnt = 1;
  while(1){
    cin >> w >> h;
    if(w == 0 || h == 0) break;

    int tx,ty;
    int kx,ky;
    cin >>tx >> ty >> kx >> ky;
    tx--;ty--;kx--;ky--;

    int mas[50][50];

    for(int i = 0;i < h;i++){
      for(int j = 0;j < w;j++){
        cin >> mas[i][j];
      }
    }

    queue<Data> que;
    Data tmp;
    tmp.c = 0; tmp.tx = tx; tmp.ty = ty; tmp.kx = kx; tmp.ky = ky;
    que.push(tmp);

    while(!que.empty()){
      tmp = que.front(); que.pop();
      if(tmp.tx == tmp.kx && tmp.ty == tmp.ky){
        cout << tmp.c << endl;
        break;
      }

      memo[tmp.tx][tmp.ty][tmp.kx][tmp.ky] = cnt;

      if(tmp.c < 100){
        tmp.c++;
        for(int tt = 0;tt < 4;tt++){
          Data d;
          d.c = tmp.c;
          int ttx = tmp.tx + ido1[tt];
          int tty = tmp.ty + ido2[tt];
          if(ttx >= 0 && ttx < w && tty >= 0 && tty < h && mas[tty][ttx] == 0){
            d.tx = ttx;
            d.ty = tty;
          }else{
            d.tx = ttx - ido1[tt];
            d.ty = tty - ido2[tt];
          }

          int tkx = tmp.kx + ido3[tt];
          int tky = tmp.ky + ido4[tt];

          if(tkx >= 0 && tkx < w && tky >= 0 && tky < h && mas[tky][tkx] == 0){
            d.kx = tkx;
            d.ky = tky;
          }else{
            d.kx = tkx - ido3[tt];
            d.ky = tky - ido4[tt];
          }

          if(memo[d.tx][d.ty][d.kx][d.ky] != cnt){
            que.push(d);
          }
        }
      }
    }

    if(que.empty()){
      cout <<"NA" << endl;
    }

    cnt++;
  }

  return 0;
}