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(102)
	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]
			}
			if now==next {
				continue
			}
			next.Turn += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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>
#include <queue>
#include <algorithm>
using namespace std;
typedef pair<int,int> P;

int w,h,ans;
int a[51][51];
bool f[51][51][51][51];
int dx[4] = {0,0,1,-1};
int dy[4] = {1,-1,0,0};

struct cost{
	P tp,kp;
	int cnt;
};

void solve(struct cost c){
	queue<struct cost> q;
	q.push( c );
	ans = -1;
	for(int ty=0 ; ty < h ; ty++ ){
		for(int tx=0 ; tx < w ; tx++ ){
			for(int ky=0 ; ky < h ; ky++ ){
				for(int kx=0 ; kx < w ; kx++ ){
					f[ty][tx][ky][kx] = false;
				}
			}
		}
	}

	while( !q.empty() ){
		struct cost now = q.front(), next;
		q.pop();
		int tx = now.tp.first;
		int ty = now.tp.second;
		int kx = now.kp.first;
		int ky = now.kp.second;
		next.cnt = now.cnt + 1;
		if( f[ty][tx][ky][kx] ){
			continue;
		}else{
			f[ty][tx][ky][kx] = true;
		}
		if( now.cnt == 100 ){
			break;
		}
		if( tx == kx && ty == ky ){
			ans = now.cnt;
			break;
		}

		for(int i=0 ; i < 4 ; i++ ){
			int tmx = tx + dx[i];
			int tmy = ty + dy[i];
			int kmx = kx - dx[i];
			int kmy = ky - dy[i];
			if( tmx < 0 || tmy < 0 || tmx >= w || tmy >= h || a[tmy][tmx] ){
				P tp(tx,ty);
				next.tp = tp;
			}else{
				P tp(tmx,tmy);
				next.tp = tp;
			}
			if( kmx < 0 || kmy < 0 || kmx >= w || kmy >= h || a[kmy][kmx] ){
				P kp(kx,ky);
				next.kp = kp;
			}else{
				P kp(kmx,kmy);
				next.kp = kp;
			}
			q.push( next );
		}
	}
}

int main(){
	while( cin >> w >> h , w||h ){
		int tx, ty, kx, ky;
		cin >> tx >> ty >> kx >> ky;
		tx--; ty--; kx--; ky--;
		for(int y=0 ; y < h ; y++ ){
			for(int x=0 ; x < w ; x++ ){
				cin >> a[y][x];
			}
		}

		struct cost c;
		P tp(tx,ty), kp(kx,ky);
		c.tp = tp;
		c.kp = kp;
		c.cnt = 0;
		solve( c );
		if( ans == -1 ){
			cout << "NA" << endl;
		}else{
			cout << ans << endl;
		}
	}
}

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 + 100][N + 100] = {false};
bool move[N + 100][N + 100][N + 100][N + 100];

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;
}