Go: package main

import (
	"fmt"
	"math"
	"container/heap"
)

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 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)
			}
		}
	}
	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<iostream>
#include<queue>
#include<algorithm>
#include<map>
using namespace std;

int w,h;
int tx,ty,kx,ky;
class point{
	public:
	int x;
	int y;
};


class State{//?????????????????????????????????????????¨????????????
	public:
	int x1;
	int y1;
	int x2;
	int y2;
	int ans;
	State(int a,int b,int c,int d,int aa){
		x1=a;
		y1=b;
		x2=c;
		y2=d;
		ans=aa;
	}

};


map< pair<pair<int,int>,pair<int,int> >,bool>visited;



const int WIDTH=55;
const int HEIGHT=55;
const int OUT=-3;
int table[WIDTH][HEIGHT];

int main(){

	while(true){
		cin>>w>>h;
		if(w==0&&h==0)break;
		cin>>tx>>ty;
		cin>>kx>>ky;
		for(int i=0;i<=WIDTH;i++){
			for(int j=0;j<=HEIGHT;j++)table[i][j]=OUT;//??????
		}
		for(int i=1;i<=h;i++){
			for(int j=1;j<=w;j++){
				cin>>table[i][j];
			}
		}
	
		State first(tx,ty,kx,ky,0);//???????????¶???
		queue<State>bfs;
		bfs.push(first);
	
		visited[make_pair(make_pair(tx,ty),make_pair(tx,ty))]=true;
	
	
	
		int moveX1[]={1,0,-1,0},moveY1[]={0,1,0,-1};//?????????????????????
	
		int moveX2[]={-1,0,1,0},moveY2[]={0,-1,0,1};//?????????????????????
	
		bool ok=false;
		while(!bfs.empty()){
			int x1,y1,x2,y2,ans;
			State now=bfs.front();
			bfs.pop();
			x1=now.x1;
			y1=now.y1;
			x2=now.x2;
			y2=now.y2;
			ans=now.ans;
		
		
			//\\cout<<x1<<" "<<y1<<" "<<x2<<" "<<y2<<" "<<ans<<endl;
			if(x1==x2&&y1==y2){
				cout<<ans<<endl;//??????????????????????????????
				ok=true;
					break;
				}	
			if(ans>100){
				cout<<"NA"<<endl;
				ok=true;
				break;
			}

			//??\???????¬??????????
			int nextX1,nextY1,nextX2,nextY2;//??????????¬??????§?¨?
			int place1,place2;//??????????¬??????´???(????????????????????????)
			//4??????????????????
			for(int i=0;i<4;i++){
		
				nextX1=x1+moveX1[i];
				nextY1=y1+moveY1[i];
				nextX2=x2+moveX2[i];
				nextY2=y2+moveY2[i];
			
				place1=table[nextX1][nextY1];
				place2=table[nextX2][nextY2];
			
				if(place1==OUT||place1==1){//????????????????????????????????????????????????
					nextX1=x1;//????????????
					nextY1=y1;//????????????
				}
			
				if(place2==OUT||place2==1){
					nextX2=x2;//????????????
					nextY2=y2;//????????????
				}
			
				if(visited[make_pair(make_pair(nextX1,nextY1),make_pair(nextX2,nextY2))]==false){
					State next(nextX1,nextY1,nextX2,nextY2,ans+1);
					bfs.push(next);//ans???1????????????????????\????????\??????
					visited[make_pair(make_pair(nextX1,nextY1),make_pair(nextX2,nextY2))]=true;//?¨??????????
					//cout<<nextX1<<" "<<nextY1<<" "<<nextX2<<" "<<nextY2<<" "<<endl;
				}
			}
		
		}
	
		if(!ok)cout<<"NA"<<endl;
	}
	return 0;
}


/*



0 0 0 0 1 0
0 1 0 0 0 0
0 1 0 0 0 0
0 0 0 1 0 0
0 0 0 0 0 1
0 0 0 0 0 0


*/