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 ans <= now.Turn {
			continue
		}
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		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>
using namespace std;
const int N = 50;
#define dx(y, x) field[(y) + 10][(x) + 10]
#define dy(a, b, c, d) move[(a) + 10][(b) + 10][(c) + 10][(d) + 10]
#define FOR(a, b) for (int (a) = 0; (a) < (int)(b); ++(a))

int field[N + 25][N + 25] = {false};
bool move[N + 25][N + 25][N + 25][N + 25];

class C{
    public:
        int ty, tx, ky, kx, step;
        C(int tty, int ttx, int kky, int kkx, int s);
};

C::C(int tty, int ttx, int kky, int kkx, int s){
    ty = tty;
    tx = ttx;
    ky = kky;
    kx = kkx;
    step = s;
}

int main(){

    int w, h, stx, sty, skx, sky;
    while(cin >>w >>h){
        if(w == 0 && h == 0) break;

        FOR(i, (N + 100)){
            FOR(j, (N + 100)){
                field[i][j] = -1;
            }
        }

        cin >>stx >>sty >>skx >>sky;
        --stx; --sty; --skx; --sky;

        FOR(i, h){
            FOR(j, w){
                cin >>dx(i, j);
            }
        }

        queue<C> qu;
        C cls(sty, stx, sky, skx, 0);
        qu.push(cls);
        dy(sty, stx, sky, skx) = true;

        int cnt = 0;
        bool endFlg = false;
        int mx[] = {0, 1, 0, -1};
        int my[] = {-1, 0, 1, 0};

        while(!qu.empty()){
            C now = qu.front(); qu.pop();

            if(now.step >= 100) break;
            if(now.ty == now.ky && now.tx == now.kx){
                endFlg = true;
                cout <<now.step <<endl;
                break;
            }

            FOR(i, 4){
                FOR(j, 4){
                    int nty = now.ty + my[i];
                    int ntx = now.tx + mx[i];
                    int nky = now.ky + (my[i] * -1);
                    int nkx = now.kx + (mx[i] * -1);
                    if(!dy(nty, ntx, nky, nkx) && !(dx(nty, ntx) == 1 && dx(nky, nkx) == 1) && dx(nty, ntx) != -1 && dx(nky, nkx) != -1){

                        if(dx(nty, ntx) == 1){
                            nty = now.ty; ntx = now.tx;
                        }
                        if(dx(nky, nkx) == 1){
                            nky = now.ky; nkx = now.kx;
                        }
                        if(dy(nty, ntx, nky, nkx)) continue;

                        C tmp2(nty, ntx, nky, nkx, now.step + 1);
                        qu.push(tmp2);
                        dy(nty, ntx, nky, nkx) = true;
                    }
                }
            }
        }

        if(!endFlg) cout <<"NA" <<endl;
    }
    return 0;
}