Go: package main

import (
	"container/heap"
	"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)
	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)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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 += 1
			if next.Turn < 100 {
				heap.Push(&pq, next)
			}
		}
	}
	fmt.Println("NA")
}

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

bool f[50][50];
bool h[50][50][50][50];

class State
{
public:
	int lx,ly,rx,ry,c;
	State(int lx, int ly, int rx, int ry, int c)
	:lx(lx),ly(ly),rx(rx),ry(ry),c(c)
	{}
};
int main()
{
	int W,H;
	while(cin >> W >> H, (W||H))
	{
		memset(h,0,sizeof(h));

		int lx,ly,rx,ry;
		cin >> lx >> ly >> rx >> ry;

		lx--; ly--;
		rx--; ry--;

		for(int i=0; i<H; i++)
		for(int j=0; j<W; j++)
			cin >> f[j][i];

		queue<State> q;
		q.push(State(lx,ly,rx,ry,0));

		bool g=false;
		while(!q.empty())
		{
			State s = q.front(); q.pop();
			if(s.c >= 100) break;

			if(s.lx==s.rx&&s.ly==s.ry)
			{
				g=true;
				cout << s.c << endl;
				break;
			}

			for(int i=0; i<4; i++)
			{
				int tlx=s.lx+dx[i], tly=s.ly+dy[i];
				int trx=s.rx+dx[(i+2)%4], ttry=s.ry+dy[(i+2)%4];

				if(tlx<0||tlx>=W||tly<0||tly>=H||f[tlx][tly])
				{
					tlx = s.lx;
					tly = s.ly;
				}
				if(trx<0||trx>=W||ttry<0||ttry>=H||f[trx][ttry])
				{
					trx = s.rx;
					ttry = s.ry;
				}

				if(h[tlx][tly][trx][ttry]) continue;
				h[tlx][tly][trx][ttry]=1;
				
				q.push(State(tlx,tly,trx,ttry,s.c+1));

			}
		}

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

	}
}

C++: #include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
const int Dx[] = {-1,0,1,0},Dy[] = {0,-1,0,1};
#define INF 1e+8
#define EPS 1e-8
#define rep(i,j) for(int i = 0; i < (j); i++)
#define reps(i,j,k) for(int i = (j); i < (k); i++)
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> Pii;
int X,Y;
int l,m,n,o;
bool vis[52][52][52][52];
class P{
	public:
	int ax,ay,bx,by;
	int cnt;
	P(int ax,int ay,int bx,int by,int cnt):ax(ax),ay(ay),bx(bx),by(by),cnt(cnt){}
};
bool c(int stage[52][52],int f,int i){
	if(f == 0){
		if(o+Dy[i] >= 0 && o+Dy[i] <= Y && n+Dx[i] >= 0 && n+Dx[i] <= X &&
			m+dy[i] >= 0 && m+dy[i] <= Y && l+dx[i] >= 0 && l+dx[i] <= X)return true;
		else return false;
	}
	if(f == 1){
		if(m+dy[i] >= 0 && m+dy[i] <= Y && l+dx[i] >= 0 && l+dx[i] <= X)return true;
		else return false;
	}
	if(f == 2){
		if(o+Dy[i] >= 0 && o+Dy[i] <= Y && n+Dx[i] >= 0 && n+Dx[i] <= X)return true;
		else return false;
	}
}
int main(){
	while(scanf("%d%d",&X,&Y),(X|Y)){
		int tx,ty;
		scanf("%d%d",&tx,&ty);
		int kx,ky;
		scanf("%d%d",&kx,&ky);
		int stage[52][52];
		rep(i,Y)rep(j,X)scanf("%d",&stage[i][j]);
		int check = -1;
		queue<P> Q;
		Q.push(P(tx-1,ty-1,kx-1,ky-1,0));
		X--;Y--;
		memset(vis,false,sizeof(vis));
		while( Q.size() ){
			P p = Q.front();Q.pop();
			if(p.cnt == 100)break;
			if(p.ax == p.bx && p.ay == p.by){check=p.cnt;break;}
			l = p.ax;m = p.ay;n = p.bx,o = p.by;
			//printf("D:%d %d %d %d\n",l,m,n,o);
			rep(i,4){
				if(stage[m+dy[i]][l+dx[i]] == 0 && c(stage,1,i) && !vis[l+dx[i]][m+dy[i]][n][o] &&
					(stage[o+Dy[i]][n+Dx[i]] == 1 || o+Dy[i] < 0 || o+Dy[i] > Y || n+Dx[i] < 0 || n+Dx[i] > X) ){
					Q.push(P(l+dx[i],m+dy[i],n,o,p.cnt+1));
					vis[l+dx[i]][m+dy[i]][n][o] = true;
				}
				else if(stage[o+Dy[i]][n+Dx[i]] == 0 && c(stage,2,i) && !vis[l][m][n+Dx[i]][o+Dy[i]] &&
					(stage[m+dy[i]][l+dx[i]] == 1 || m+dy[i] < 0 || m+dy[i] > Y || l+dx[i] < 0 || l+dx[i] > X) ){
					Q.push(P(l,m,n+Dx[i],o+Dy[i],p.cnt+1));
					vis[l][m][n+Dx[i]][o+Dy[i]] = true;
				}
				else if(c(stage,0,i) && stage[m+dy[i]][l+dx[i]] == 0 && stage[o+Dy[i]][n+Dx[i]] == 0 && !vis[l+dx[i]][m+dy[i]][n+Dx[i]][o+Dy[i]]){
					Q.push(P(l+dx[i],m+dy[i],n+Dx[i],o+Dy[i],p.cnt+1));
					vis[l+dx[i]][m+dy[i]][n+Dx[i]][o+Dy[i]] = true;
				}
			}
		}
		(check != -1) ? printf("%d\n",check) : puts("NA");
	}
	return 0;
}