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<cstdio>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<queue>
#include<string.h>
#include<string>
#include<vector>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
struct X
{
	int tx, ty, t, kx, ky;
};
int java[51][51][51][51] = { 0 };
int main()
{
	int w, h, map[52][52] = { 0 };
		int mx[4] = { 0,1,0,-1 }, my[4] = { 1,0,-1,0 };
		while (1)
		{
			queue<X> que;
			X c;
			cin >> w >> h;
			if (w == 0 && h == 0)
				break;
			memset(java, 0, sizeof(java));
			cin >> c.tx >> c.ty >> c.kx >> c.ky;
			c.t = 0;
			que.push(c);
			rep1(i, h)
			{
				rep1(j, w)
				{
					cin >> map[i][j];
				}
			}
			/*?£???????*/
			rep(i, h + 2)//n???????????°,m????¨??????°
			{
				map[i][0] = 1;
				map[i][w + 1] = 1;
			}
			rep(i, w + 2)
			{
				map[0][i] = 1;
				map[h + 1][i] = 1;
			}
			while (!que.empty())
			{
				c = que.front();
				que.pop();
				java[c.tx][c.ty][c.kx][c.ky] = 1;
				if (c.tx == c.kx&&c.ty == c.ky||c.t >= 100)
				{
					break;
				}
				c.t++;
				rep(i, 4)
				{
					if (java[c.tx + mx[i]][c.ty + my[i]][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
					{
						c.tx += mx[i];
						c.ty += my[i];
						c.kx -= mx[i];
						c.ky -= my[i];
						que.push(c);
						java[c.tx][c.ty][c.kx][c.ky] = 1;
						c.tx -= mx[i];
						c.ty -= my[i];
						c.kx += mx[i];
						c.ky += my[i];
					}
					else if (java[c.tx][c.ty][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 1 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
					{
						c.kx -= mx[i];
						c.ky -= my[i];
						que.push(c);
						java[c.tx][c.ty][c.kx][c.ky] = 1;
						c.kx += mx[i];
						c.ky += my[i];
					}
					else if (java[c.tx + mx[i]][c.ty + my[i]][c.kx][c.ky] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] == 1)
					{
						c.tx += mx[i];
						c.ty += my[i];
						que.push(c);
						java[c.tx][c.ty][c.kx][c.ky] = 1;
						c.tx -= mx[i];
						c.ty -= my[i];
					}
				}
			}
			if (c.t < 100&&!que.empty())
				cout << c.t << endl;
			else
				cout << "NA" << endl;
		}
	return 0;
}

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

class Node {
public:
  int tx, ty;
  int kx, ky;
  int time;
  Node(int tx = 0, int ty = 0, int kx = 0, int ky = 0, int time = 0):
    tx(tx), ty(ty), kx(kx), ky(ky), time(time) {}

  bool operator <(const Node &n) const {
    if(tx != n.tx) return tx < n.tx;
    if(ty != n.ty) return ty < n.ty;
    if(kx != n.kx) return kx < n.kx;
    if(ky != n.ky) return ky < n.ky;
    return false;
  }
};

int main() {
  while(1) {
    int X, Y;
    cin >> X >> Y;
    if(X == 0 && Y == 0) break;
    int tx, ty;
    cin >> tx >> ty;
    int kx, ky;
    cin >> kx >> ky;
    int data[Y][X];
    for(int i = 0; i < Y; i++) {
      for(int j = 0; j < X; j++) {
	cin >> data[i][j];
      }
    }
    queue<Node> Q;
    set<Node> visited;
    Q.push(Node(tx-1, ty-1, kx-1, ky-1, 0));
    int d[4][2] = {{1,0},{0,1},{-1,0},{0,-1}};
    int ans = -1;
    while(!Q.empty()) {
      Node n = Q.front();
      Q.pop();
      if(visited.find(n) != visited.end()) continue;
      visited.insert(n);
      if(n.tx == n.kx && n.ty == n.ky) {
	ans = n.time;
	break;
      }
      for(int i = 0; i < 4; i++) {
	int ntx = n.tx + d[i][0];
	int nty = n.ty + d[i][1];
	if(ntx < 0 || ntx >= X) ntx = n.tx;
	if(nty < 0 || nty >= Y) nty = n.ty;
	if(data[nty][ntx] == 1) {
	  ntx = n.tx;
	  nty = n.ty;
	}
	int nkx = n.kx - d[i][0];
	int nky = n.ky - d[i][1];
	if(nkx < 0 || nkx >= X) nkx = n.kx;
	if(nky < 0 || nky >= Y) nky = n.ky;
	if(data[nky][nkx] == 1) {
	  nkx = n.kx;
	  nky = n.ky;
	}
	if(visited.find(Node(ntx, nty, nkx, nky, n.time+1)) == visited.end())
	  Q.push(Node(ntx, nty, nkx, nky, n.time+1));
      }
    }
    if(ans == -1) {
      cout << "NA" << endl;
    } else {
      cout << ans << endl;
    }
  }
  return 0;
}