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(101)
	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 v, ok := memo[now.Person]; ok && v <= now.Turn {
			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 += 1
			if next.Turn < 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				pq = append(pq, next)
			}
		}
	}
	if ans == 101 {
		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 <queue>
#include <map>
#include <utility>

using namespace std;

typedef pair<int,int> P1;
typedef pair<P1,P1> P2;
typedef pair<P2,int> P;

#define CHECK(X,Y) (0<=(X)&&(X)<(Y))

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

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	int d[50][50];
	while(scanf("%d %d",&X,&Y),X||Y) {
		scanf("%d %d",&tx,&ty);
		scanf("%d %d",&kx,&ky);
		for(int j=0;j<Y;j++) {
			for(int i=0;i<X;i++) {
				scanf("%d",&d[i][j]);
			}
		}
		queue<P> que;
		map<P2,bool> mp;
		que.push(P(P2(P1(tx-1,ty-1),P1(kx-1,ky-1)),0));
		bool na=true;
		while(!que.empty()) {
			P p=que.front();que.pop();
			tx=p.first.first.first,ty=p.first.first.second;
			kx=p.first.second.first,ky=p.first.second.second;
			if(tx==kx&&ty==ky) {
				na=false;
				printf("%d\n",p.second);
				break;
			}
			mp[p.first]=true;
			for(int i=0;i<4;i++) {
				int ntx=tx,nty=ty,nkx=kx,nky=ky;
				if(CHECK(ntx+dx[i],X)&&CHECK(nty+dy[i],Y)&&!d[ntx+dx[i]][nty+dy[i]]) ntx+=dx[i],nty+=dy[i];
				if(CHECK(nkx-dx[i],X)&&CHECK(nky-dy[i],Y)&&!d[nkx-dx[i]][nky-dy[i]]) nkx-=dx[i],nky-=dy[i];
				P2 p2(P1(ntx,nty),P1(nkx,nky));
				if(mp.find(p2)==mp.end()) {
					que.push(P(p2,p.second+1));
				}
			}
		}
		if(na) printf("NA\n");
	}
}

C++: #include <iostream>
#include <queue>

#define INF 10000
#define N_MAX 50
#define M_MAX 50

using namespace std;

typedef pair<int,int> P;
typedef pair<P,P> PP;

short int d[N_MAX][M_MAX][N_MAX][M_MAX];

int X,Y;
int tx,ty,kx,ky;
int ans;

int map[N_MAX][M_MAX];

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

bool bfs();

int main () {
	
	while (1) {
		cin>>X>>Y;
		if (X==0&&Y==0) {
			break;
		}
		cin>>tx>>ty>>kx>>ky;
		tx--;ty--;kx--;ky--;
		for (int i=0; i<Y; i++) {
			for (int j=0; j<X; j++) {
				cin>>map[i][j];
				for (int k=0; k<Y; k++) {
					for (int l=0; l<X; l++) {
						d[i][j][k][l]=INF;
					}
				}
			}
		}
		
		if (bfs()) {
			cout << ans << endl;
		}
		else{
			cout << "NA" << endl;
		}
	}
}

bool bfs(){
	queue<PP> que;
	que.push(PP(P(ty,tx),P(ky,kx)));
	d[ty][tx][ky][kx]=0;

	while(que.size()){
		PP p;
		p = que.front();
		que.pop();
		if (d[p.first.first][p.first.second][p.second.first][p.second.second]>=100) {
			return false;
		}
		if(p.first.first==p.second.first&&p.first.second==p.second.second){
			ans = d[p.first.first][p.first.second][p.second.first][p.second.second];
			return true;
		}
		for (int i=0; i<4; i++) {
			int ntx=p.first.second+dx[i],nty=p.first.first+dy[i];
			int nkx=p.second.second-dx[i],nky=p.second.first-dy[i];
			
			int flag=2;
			if (!(0<=ntx&&ntx<X&&0<=nty&&nty<Y&&map[nty][ntx]!=1)) {
				ntx-=dx[i];nty-=dy[i];
				flag--;
			}
			if (!(0<=nkx&&nkx<X&&0<=nky&&nky<Y&&map[nky][nkx]!=1)) {
				nkx+=dx[i];nky+=dy[i];
				flag--;
			}
			
			if (flag!=0&&d[nty][ntx][nky][nkx]==INF) {
				que.push(PP(P(nty,ntx),P(nky,nkx)));
				d[nty][ntx][nky][nkx] = d[p.first.first][p.first.second][p.second.first][p.second.second]+1;
			}
			
		}
	}
	
	return false;
}

C++: #include<iostream>
#include<algorithm>
#include<queue>
#include<cmath>
using namespace std;
struct Data{
    int tx,ty,kx,ky;
    int t;
    Data(){};
    Data(int a,int b,int c,int d,int _t){
        tx = a,ty = b,kx = c,ky = d,t = _t;
    }
};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
bool vis[60][60][60][60];
bool fi[100][100];
int w,h;
bool c(int x,int y){
    if(0 <= x && x < w && 0 <= y && y < h)return true;
}
bool C(int x,int y){
    return fi[x][y];
}
int main(){
    while(cin>>w>>h,w){
        int tx,ty,kx,ky;
        cin>>tx>>ty>>kx>>ky;
        tx--,ty--,kx--,ky--;
        for(int i = 0;i < h;i++)for(int j = 0;j < w;j++)cin>>fi[i][j];
        queue<Data> Q;
        Q.push(Data(tx,ty,kx,ky,0));
        while(!Q.empty()){
            Data D = Q.front();Q.pop();
            if(vis[D.tx][D.ty][D.kx][D.ky])continue;
            if(D.t>=100){
                cout<<"NA"<<endl;
                break;
            }
            if(abs(D.tx - D.kx) + abs(D.ty - D.ky) == 1){
                cout<<D.t<<endl;
                break;
            }
            for(int i = 0;i < 4;i++){
                int ntx = tx + dx[i],nty = ty + dy[i];
                int nkx = kx + dx[(i+2)%4],nky = ky + dy[(i+2)%4];
                if(c(ntx,nty) || C(ntx,nty)){
                    ntx = tx,nty = ty;
                }
                if(c(nkx,nky) || C(nkx,nky)){
                    nkx = kx,nky = ky;
                }
                if(vis[ntx][nty][nkx][nky])continue;
                vis[ntx][nty][nkx][nky] = true;
                Q.push(Data(ntx,nty,nkx,nky,D.t+1));
            }
        }
    }
    return 0;
}