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<iostream>
#include<map>

using namespace std;

int X,Y;
int fld[52][52];
map<long long, int> memo;

void erase(){
	for(int i=0; i<52; i++)
		for(int j=0; j<52; j++)
			fld[i][j] = 1;
}

int solve(int tx, int ty, int kx, int ky, int count){
	if(tx == kx && ty == ky)
		return count-1;
	if(count >= 100)
		return 100;
	if(memo.find(tx + ty*100 + kx*100*100 + ky*100*100*100) != memo.end())
		return memo[tx + ty*100 + kx*100*100 + ky*100*100*100];
	int ttx = tx,tty = ty,kkx = kx,kky = ky;
	int tmp1=100,tmp2 = 100,tmp3 = 100,tmp4 = 100;
	
	ttx++;
	kkx--;
	if(fld[tty][ttx])
		ttx--;
	if(fld[kky][kkx])
		kkx++;
	if(ttx != tx || kkx != kx)
		tmp1 = solve(ttx,tty,kkx,kky,count+1);
	
	ttx = tx,tty = ty,kkx = kx,kky = ky;
	ttx--;
	kkx++;
	if(fld[tty][ttx])
		ttx++;
	if(fld[kky][kkx])
		kkx--;
	if(ttx != tx || kkx != kx)
		tmp2 = solve(ttx,tty,kkx,kky,count+1);
	
	ttx = tx,tty = ty,kkx = kx,kky = ky;
	tty++;
	kky--;
	if(fld[tty][ttx])
		tty--;
	if(fld[kky][kkx])
		kky++;
	if(tty != ty || kky != ky)
		tmp3 = solve(ttx,tty,kkx,kky,count+1);
	
	ttx = tx,tty = ty,kkx = kx,kky = ky;
	tty--;
	kky++;
	if(fld[tty][ttx])
		tty++;
	if(fld[kky][kkx])
		kky--;
	if(tty != ty || kky != ky)
		tmp4 = solve(ttx,tty,kkx,kky,count+1);
	
	if(tmp1 > tmp2)
		tmp1 = tmp2;
	if(tmp1 > tmp3)
		tmp1 = tmp3;
	if(tmp1 > tmp4)
		tmp1 = tmp4;
	memo[tx + ty*100 + kx*100*100 + ky*100*100*100] = tmp1;
	return tmp1;
}

int main(){
	int tx,ty,kx,ky;
	while(true){
		cin >> X >> Y;
		if(!X && !Y)
			return 0;
		memo.clear();
		cin >> tx >> ty >> kx >> ky;
		for(int i=1; i<=Y; i++)
			for(int j=1; j<=X; j++)
				cin >> fld[i][j];
		int ans = solve(tx,ty,kx,ky,0);
		if(ans == 100)
			cout << "NA\n";
		else
			cout << ans << endl;
	}
}