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;

#define MAX 51

int xy[MAX][MAX];
int cost[MAX][MAX][MAX][MAX];
int X,Y;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int co;
  state(){}
  state(int tx,int ty,int kx,int ky,int co):
    tx(tx),ty(ty),kx(kx),ky(ky),co(co){}
};

int solve(int tx,int ty,int kx,int ky){

  memset(cost,101,sizeof(cost));

  queue<state> q;
  q.push( state(tx,ty,kx,ky,0) );

  while( !q.empty() ){
    state p=q.front();
    q.pop();

    if(p.co==100){
      break;
    }

    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;

    for(int i=0;i<4;i++){
      
      if(kx+dx[i]*-1 < 0 || ky+dy[i]*-1 <0 || kx+dx[i]*-1 >= X || ty+dy[i]*-1 >= Y || 
	 tx+dx[i] < 0 || ty+dy[i] <0 || tx+dx[i] >= X || ty+dy[i] >= Y )
	continue;

      cost[tx][ty][kx][ky]=p.co;

      if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] < p.co)
	continue;

      if( xy[ty+dy[i]][tx+dx[i]]==1 || xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	continue;
      
      if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1){
	if(p.co+1>=100) return -1;
	return p.co+1;
      }

      q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );

    }
  }
  return -1;
} 

main(){
  
  int i,j;
  int kx,ky,tx,ty;
  int n;

  while(1){
    
    cin >> X >> Y;

    if(X==0 && Y==0) break;
    
    cin >> tx >> ty;
    cin >> kx >> ky;
    
    for(i=0;i<Y;i++){
      for(j=0;j<X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx-1,ty-1,kx-1,ky-1);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <string>
#include <algorithm>
#include <utility>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define INF (2000000000)
#define MOD (1000000007)
using namespace std;

typedef vector<int> VI;
typedef vector<int>::iterator VII;
typedef vector<double> VD;
typedef vector<double>::iterator VDI;
typedef pair<int, int> P;


typedef struct
{
	int tx, ty, kx, ky;
} POS;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};

int maze[100][100];
int X, Y;
POS f;
int d[55][55][55][55];

int search()
{
	queue<POS> que;
	
	for (int i = 0; i < 55; i++){
		for (int j = 0; j < 55; j++){
			for (int k = 0; k < 55; k++){
				for (int l = 0; l < 55; l++){
					d[i][j][k][l] = INF;
				}
			}
		}
	}
	
	que.push(f);
	d[f.tx][f.ty][f.kx][f.ky] = 0;
	
	while (que.size()){
		POS now = que.front();
		que.pop();
		
		//printf("%d %d %d %d\n", now.tx, now.ty, now.kx, now.ky);
		
		if (now.tx == now.kx && now.ty == now.ky){
			return (d[now.tx][now.ty][now.kx][now.ky]);
		}
		
		for (int i = 0; i < 4; i++){
			POS to;
			if (maze[now.tx + dx[i]][now.ty + dy[i]] && maze[now.kx - dx[i]][now.ky - dy[i]]){
				continue;
			}
			
			if (maze[now.tx + dx[i]][now.ty + dy[i]]){
				to.tx = now.tx;
				to.ty = now.ty;
			}
			else {
				to.tx = now.tx + dx[i];
				to.ty = now.ty + dy[i];
			}
			
			if (maze[now.kx - dx[i]][now.ky - dy[i]]){
				to.kx = now.kx;
				to.ky = now.ky;
			}
			else {
				to.kx = now.kx - dx[i];
				to.ky = now.ky - dy[i];
			}
			
			to.tx = now.tx + dx[i];
			to.ty = now.ty + dy[i];
			to.kx = now.kx - dx[i];
			to.ky = now.ky - dy[i];
			
			//printf("%d %d %d %d\n", to.tx, to.ty, to.kx, to.ky);
			
			if (d[to.tx][to.ty][to.kx][to.ky] == INF && d[now.tx][now.ty][now.kx][now.ky] < 99){
				que.push(to);
				d[to.tx][to.ty][to.kx][to.ky] = d[now.tx][now.ty][now.kx][now.ky] + 1;
			}
		}
	}
	
	return (-1);
}

int main()
{
	while (scanf("%d %d", &X, &Y), X + Y){
		scanf("%d %d", &f.tx, &f.ty);
		scanf("%d %d", &f.kx, &f.ky);
		
		for (int i = 0; i < 100; i++){
			for (int j = 0; j < 100; j++){
				maze[i][j] = 1;
			}
		}
		
		for (int i = 1; i <= Y; i++){
			for (int j = 1; j <= X; j++){
				scanf("%d", &maze[j][i]);
			}
		}
		
		//for (int i = 0; i <= Y + 1; i++){
		//	for (int j = 0; j <= X + 1; j++){
		//		printf("%d ", maze[j][i]);
		//	}
		//	puts("");
		//}
		
		int r = search();
		if (r != -1) printf("%d\n", r);
		else puts("NA");
	}
	
	return 0;
}