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 _, ok := memo[now.Person]; ok {
			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 <bits/stdc++.h>

#define rep_(v, f, l) for (int v = (f); v < (l); ++v)
#define rep(v, n) rep_(v, 0, n)
#define lep(v, n) rep_(v, 1, n + 1)

using namespace std;

typedef long long int lint;

static inline int in(){ int x; scanf("%d", &x); return x; }
static inline lint inl(){ lint x; scanf("%lld", &x); return x; }

struct State {
    int tx, ty;
    int kx, ky;
    State(int tx, int ty, int kx, int ky) : tx(tx), ty(ty), kx(kx), ky(ky) {}
    bool isComplete(){
        return tx == kx && ty == ky;
    }
};

int range(int maxi, int x, int mini)
{
    if (maxi <= x) return maxi;
    if (mini >= x) return mini;
    return x;
}

int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
char visited[64][64][64][64];

int main()
{
    int w, h;
    while (w = in(), h = in(), w){
        int tx, ty, kx, ky;
        tx = in();
        ty = in();
        kx = in();
        ky = in();

        int field[128][128] = {};
        rep(i, h){
            rep(j, w){
               field[i + 1][j + 1] = in();
            }
        }

        queue<State> Q;
        State init = State(tx, ty, kx, ky);
        Q.push(init);
        memset(visited, 0, sizeof(visited));
        visited[tx][ty][kx][ky] = 1;
        bool ok = false;
        rep(turn, 101){
            queue<State> nQ;
            while (!Q.empty()){
                State state = Q.front();
                Q.pop();
                if (state.isComplete()){
                    ok = true;
                    break;
                }
                rep(i, 4){
                    State n = state;
                    n.tx = range(w, n.tx + dx[i], 1);
                    n.kx = range(w, n.kx - dx[i], 1);
                    n.ty = range(h, n.ty + dy[i], 1);
                    n.ky = range(h, n.ky - dy[i], 1);
                    if (field[n.ty][n.tx]){
                        n.ty = state.ty;
                        n.tx = state.tx;
                    }
                    if (field[n.ky][n.kx]){
                        n.ky = state.ky;
                        n.kx = state.kx;
                    }

                    if (!visited[n.tx][n.ty][n.kx][n.ky]){
                        visited[n.tx][n.ty][n.kx][n.ky] = 1;
                        nQ.push(n);
                    }
                }
            }
            if (ok){
                printf("%d\n", turn);
                break;
            }
            Q = nQ;
        }
        if (!ok){
            puts("NA");
        }
    }
    return (0);
}