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 (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)
	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)
	//pq.Push(start)
	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 pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*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 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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 <set>
#include <queue>
#include <map>
#include <stdlib.h>

using namespace std;

struct Point{
	int tx;
	int ty;
	int kx;
	int ky;
	Point( int dtx, int dty, int dkx, int dky ){
		tx = dtx;
		ty = dty;
		kx = dkx;
		ky = dky;
	}
};

Point move( int next, const Point& point, int stage[51][51] )
{
	switch( next ){
		case 0:
			return Point( stage[point.tx + 1][point.ty] ? point.tx : point.tx + 1, point.ty, stage[point.kx - 1][point.ky] ? point.kx : point.kx - 1, point.ky );
		case 1:
			return Point( stage[point.tx - 1][point.ty] ? point.tx : point.tx - 1, point.ty, stage[point.kx + 1][point.ky] ? point.kx : point.kx + 1, point.ky );
		case 2:
			return Point( point.tx, stage[point.tx][point.ty + 1] ? point.ty : point.ty + 1, point.kx, stage[point.kx][point.ky - 1] ? point.ky : point.ky - 1);
		case 3:
			return Point( point.tx, stage[point.tx][point.ty - 1] ? point.ty : point.ty - 1, point.kx, stage[point.kx][point.ky + 1] ? point.ky : point.ky + 1);
	}

	return Point(1,1,1,1);
}
	

int change( const Point& data )
{
	return data.tx + data.ty * 51 + data.kx * 51 * 51 + data.ky * 51 * 51 * 51;
}

int bfs( const Point& start, int stage[51][51] )
{
	set<int> history;
	queue<Point> q;
	map<int,int> dist;

	dist[change( start )] = 0;
	history.insert( change( start ) );

	q.push( start );
	while( !q.empty() ){
		Point u = q.front();
		if( u.tx == u.kx && u.ty == u.ky ) return dist[change( u )];

		for( int i = 0;i < 4;i++ ){
			Point v = move( i, u, stage );
			if( history.count( change( v ) ) ) continue;
			dist[change( v )] = dist[change( u )] + 1;
			history.insert( change( v ) );
			q.push( v );
		}

		q.pop();
	}
	return -1;
}
int main(int argc, char const* argv[])
{
	int X,Y;
	Point point(0,0,0,0);
	int stage[51][51];

	while( cin >> X >> Y && X != 0 ){
		cin >> point.tx >> point.ty;
		cin >> point.kx >> point.ky;
		for( int i = 0;i < 51;i++ ){
			for( int j = 0;j < 51;j++ ){
				stage[i][j] = 1;
			}
		}

		for( int i = 1;i <= Y;i++ ){
			for( int j = 1;j <= X;j++ ){
				cin >> stage[j][i];
			}
		}

		int answer = bfs( point, stage );
		if( answer == -1 ) cout << "NA" << endl;
		else cout << answer << endl;
	}

	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
using namespace std;

bool d[50][50][50][50];
int X, Y, tx, ty, kx, ky;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, mem[50][50];

bool _check(int x, int y)
{
  return x >= 0 && x < X && y >= 0 && y < Y;
}

bool check(int x1, int y1, int x2, int y2)
{
  return _check(x1, y1) && _check(x2, y2);
}

int main()
{
loop:
  cin >> X >> Y;
  if(!X)
    return 0;
  cin >> tx >> ty >> kx >> ky;
  tx--; ty--; kx--; ky--;
  for(int y = 0; y < Y; y++)
  {
    for(int x = 0; x < X; x++)
    {
      int a;
      cin >> a;
      mem[y][x] = a;
    }
  }

  fill_n((bool*)d, 50 * 50 * 50 * 50, false);
  
  queue<int> q;
  q.push(tx);
  q.push(ty);
  q.push(kx);
  q.push(ky);
  q.push(0);
  while(!q.empty())
  {
    int x1 = q.front(); q.pop();
    int y1 = q.front(); q.pop();
    int x2 = q.front(); q.pop();
    int y2 = q.front(); q.pop();
    int n = q.front(); q.pop();
    
    if(n >= 100)
    {
      cout << "NA" << endl;
      break;
    }
    
    if(y1 == y2 && x1 == x2)
    {
      cout << n << endl;
      goto loop;
    }

    for(int i = 0; i < 4; i++)
    {
      int tx1 = x1 + dx[i];
      int ty1 = y1 + dy[i];
      int tx2 = x2 - dx[i];
      int ty2 = y2 - dy[i];

      if(check(tx1, ty1, tx2, ty2) && mem[ty1][tx1])
      {
        tx1 = x1;
        ty1 = y1;
      }
      if(check(tx1, ty1, tx2, ty2) && mem[ty2][tx2])
      {
        tx2 = x2;
        ty2 = y2;
      }
      if(!check(tx1, ty1, tx2, ty2) || d[tx1][ty1][tx2][ty2])
        continue; 

      d[tx1][ty1][tx2][ty2] = true;
      q.push(tx1);
      q.push(ty1);
      q.push(tx2);
      q.push(ty2);
      q.push(n + 1);
    }
  }
  cout << "NA" << endl;
  goto loop;
}