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)
	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)
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			continue
		}
		if ans<=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)
			}
		}
	}
	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++: // 2011/07/20 Tazoe

#include <iostream>
#include <queue>
#include <map>
using namespace std;

struct state{
	int tx;
	int ty;
	int kx;
	int ky;
	int tim;
};

int main()
{
	while(true){
		int X, Y;
		cin >> X >> Y;
		if(X==0&&Y==0)
			break;

		int d[52][52];
		for(int y=0; y<=Y+1; y++)
			for(int x=0; x<=X+1; x++)
				d[y][x] = 1;

		struct state now;
		cin >> now.tx >> now.ty;
		cin >> now.kx >> now.ky;
		now.tim = 0;

		queue<struct state> que;
		que.push(now);

		map<int, bool> memo;

		for(int y=1; y<=Y; y++)
			for(int x=1; x<=X; x++)
				cin >> d[y][x];

		while(true){
			if(que.empty()){
				cout << "NA" << endl;
				break;
			}

			now = que.front();
			que.pop();

			int tk = ((now.tx*100+now.ty)*100+now.kx)*100+now.ky;
			if(memo.find(tk)!=memo.end())
				continue;
			else
				memo[tk] = true;

			if(now.tim>=100){
				cout << "NA" << endl;
				break;
			}

			if(now.tx==now.kx&&now.ty==now.ky){
				cout << now.tim << endl;
				break;
			}

			struct state nxt = now;
			if(d[nxt.ty-1][nxt.tx]==0)
				nxt.ty--;
			if(d[nxt.ky+1][nxt.kx]==0)
				nxt.ky++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty+1][nxt.tx]==0)
				nxt.ty++;
			if(d[nxt.ky-1][nxt.kx]==0)
				nxt.ky--;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx-1]==0)
				nxt.tx--;
			if(d[nxt.ky][nxt.kx+1]==0)
				nxt.kx++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx+1]==0)
				nxt.tx++;
			if(d[nxt.ky][nxt.kx-1]==0)
				nxt.kx--;
			nxt.tim++;
			que.push(nxt);
		}
	}

	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;
const int INF = 10000000;
typedef struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int cost;
  state(int tx,int ty,int kx,int ky,int cost):
      tx(tx),ty(ty),kx(kx),ky(ky),cost(cost){}
}st;
int fie[52][52];
int check[52][52][52][52];
int X,Y;
int dtx[]={0,1,0,-1};
int dty[]={1,0,-1,0};
int dkx[]={0,-1,0,1};
int dky[]={-1,0,1,0};

void init(){
  for(int i=0;i<Y;i++){
    for(int j=0;j<X;j++){
      for(int ii=0;ii<Y;ii++){
	for(int jj=0;jj<X;jj++) check[j][i][jj][ii]=INF;
	//	cout <<check[j][i][0][ii]<<endl;
      }
    }
  }
}

int solve(int tx,int ty,int kx,int ky){
  queue <st> q;
  int cost;
  int ok=0;
  q.push(state(tx,ty,kx,ky,0));
  while(!q.empty()){
    st p=q.front(); q.pop();
    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;
    cost=p.cost;

    if(tx==kx && ty==ky){ ok=1;break;}
    if(cost>=100) break;
    //cout <<tx<<" "<<ty<<" "<<kx<<" "<<ky<<" "<<cost<<endl;

    for(int i=0;i<4;i++){
      int f=0;
      if(tx+dtx[i]<0 || tx+dtx[i]>=X || ty+dty[i]<0 || ty+dty[i]>=Y) f+=1;
      if(kx+dkx[i]<0 || kx+dkx[i]>=X || ky+dky[i]<0 || ky+dky[i]>=Y) f+=10;
      if(f==11) continue;
      if((f/10)){//かずゆきいけない時
	if(fie[tx+dtx[i]][ty+dty[i]]==1 ) f+=1;
      }else if((f%10)){//たかゆきいけない時
	if(fie[kx+dkx[i]][ky+dky[i]]==1 ) f+=10;
      }else{//両方いける時
	if(fie[tx+dtx[i]][ty+dty[i]]==1 ) f+=1;
	if(fie[kx+dkx[i]][ky+dky[i]]==1 ) f+=10;
      }
      if(f>=11) continue;

      if(f/10){//かずゆきがいけない時
	if(check[tx+dtx[i]][ty+dty[i]][kx][ky]!=INF) continue;
      }else if(f%10){//たかゆきイけないとき
	if(check[tx][ty][kx+dkx[i]][ky+dky[i]]!=INF) continue;
      }else{//両方いけるとき
	if(check[tx+dtx[i]][ty+dty[i]][kx+dkx[i]][ky+dky[i]]!=INF)continue;
      }

      if(f/10){//かずゆきがいけない時
	q.push(state(tx+dtx[i],ty+dty[i],kx,ky,cost+1));
	//cout << check[tx+dtx[i]][ty+dty[i]][kx][ky] <<" ";
	check[tx+dtx[i]][ty+dty[i]][kx][ky]=cost+1;
      }
      else if(f%10){//たかゆきイけないとき
	q.push(state(tx,ty,kx+dkx[i],ky+dky[i],cost+1));
	//cout << check[tx][ty][kx+dkx[i]][ky+dky[i]] <<" ";
	check[tx][ty][kx+dkx[i]][ky+dky[i]]=cost+1;
      }
      else{//両方いけるとき
	q.push(state(tx+dtx[i],ty+dty[i],kx+dkx[i],ky+dky[i],cost+1));
	//cout << check[tx+dtx[i]][ty+dty[i]][kx+dkx[i]][ky+dky[i]] <<" ";
	check[tx+dtx[i]][ty+dty[i]][kx+dkx[i]][ky+dky[i]]=cost+1;
      }
    }
  }
  if(!ok) return 100;
  return cost;
}
main(){
  int tx,ty,kx,ky;
  while(1){
    cin >> X >> Y;
    if(X==0 && Y==0) break;
    cin >> tx >> ty;
    cin >> kx >> ky;
    init();
    for(int i=0;i<Y;i++){
      for(int j=0;j<X;j++) cin >> fie[j][i];
    }
    int res=solve(tx-1,ty-1,kx-1,ky-1);
    if(res>=100) cout << "NA" << endl;
    else cout << res << endl;
  }
}