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 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)
				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 <iostream>
#include <queue>
#include <map>
#include <string>

using namespace std;

const int dx[][4] = {{1, 0, -1, 0}, {-1, 0, 1, 0}};
const int dy[][4] = {{0, 1, 0, -1}, {0, -1, 0, 1}};

int X, Y;

bool map[50][50];
bool passed[50][50][50][50];

struct P
{
    int tx, ty;
    int kx, ky;
    int cost;

    P(int _tx, int _ty, int _kx, int _ky, int _cost) : tx(_tx), ty(_ty), kx(_kx), ky(_ky), cost(_cost) {};
};

bool check(int x, int y)
{
    return x < 0 || x >= X || y < 0 || y >= Y || map[y][x];
}

int main()
{
    int tx, ty, kx, ky, ans;
    while(cin >> X >> Y, X|Y)
    {
        ans = -1;
        memset(passed, 0, sizeof passed);
        queue<P> que;

        cin >> tx >> ty >> kx >> ky;
        tx--, ty--, kx--, ky--;

        for(int i = 0; i < Y; i++)
            for(int j = 0; j < X; j++)
                cin >> map[i][j];

        passed[tx][ty][kx][ky] = true;

        for(que.push(P(tx, ty, kx, ky, 0)); !que.empty(); que.pop())
        {
            P p = que.front();

            if(p.cost >= 100)
                break;

            if(p.tx == p.kx && p.ty == p.ky)
            {
                ans = p.cost;
                break;
            }

            for(int i = 0; i < 4; i++)
            {
                int mtx = p.tx + dx[0][i], mty = p.ty + dy[0][i];
                int mkx = p.kx + dx[1][i], mky = p.ky + dy[1][i];

                if(check(mtx, mty))
                    mtx = p.tx, mty = p.ty;
                if(check(mkx, mky))
                    mkx = p.kx, mky = p.ky;
                if(passed[mtx][mty][mkx][mky])
                    continue;

                passed[mtx][mty][mkx][mky] = true;
                que.push(P(mtx, mty, mkx, mky, p.cost + 1));
            }
        }

        if(ans == -1)
            puts("NA");
        else
            cout << ans << endl;
    }
}

C++: #include<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct Y{
int hx,hy,rx,ry,tim;
};
int mp[52][52],vh[52][52],vr[52][52];
int main(){
int n,w,h,i,j,a[2]={1,-1},b[2],g,k;
Y e;
queue<Y> q;
while(1){
	g=0;
	k=0;
	cin>>w>>h;
	if(w==0&&h==0)break;
	cin>>e.hx>>e.hy>>e.rx>>e.ry;
	e.tim=0;
	q.push(e);
	memset(mp,0,sizeof(mp));
	memset(vr,0,sizeof(vr));
	memset(vh,0,sizeof(vh));
	for(i=0;i<=h+1;i++){
		mp[i][0]=1;
		mp[i][w+1]=1;
	}
	for(i=0;i<=w+1;i++){
		mp[0][i]=1;
		mp[h+1][i]=1;
	}
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
			cin>>mp[j][i];
			if(mp[j][i]==1)k++;
		}
	}
	while(1){
		e=q.front();
		q.pop();
				if(vh[e.hy][e.hx]!=1)g++;
				if(vr[e.ry][e.rx]!=1)g++;
				vh[e.hy][e.hx]=1;
				vr[e.ry][e.rx]=1;
		if(e.tim>=100||e.hx==e.rx&&e.hy==e.ry||g==(w*h-k)*2)break;
		e.tim++;
		for(i=0;i<2;i++){
			if(mp[e.hy+a[i]][e.hx]!=1||mp[e.ry-a[i]][e.rx]!=1){
				b[0]=0;
				b[1]=0;
				if(mp[e.hy+a[i]][e.hx]!=1){
					e.hy+=a[i];
					b[0]=1;
				}
				if(mp[e.ry-a[i]][e.rx]!=1){
					e.ry-=a[i];
					b[1]=1;
				}
				if(vh[e.hy][e.hx]!=1)g++;
				if(vr[e.ry][e.rx]!=1)g++;
				vh[e.hy][e.hx]=1;
				vr[e.ry][e.rx]=1;
				q.push(e);
				if(b[0]==1)e.hy-=a[i];
				if(b[1]==1)e.ry+=a[i];
			}																									
			if(mp[e.hy][e.hx+a[i]]!=1||mp[e.ry][e.rx-a[i]]!=1){
				b[0]=0;
				b[1]=0;
				if(mp[e.hy][e.hx+a[i]]!=1){
					e.hx+=a[i];
					b[0]=1;
				}
				if(mp[e.ry][e.rx-a[i]]!=1){
					e.rx-=a[i];
					b[1]=1;
				}
				if(vh[e.hy][e.hx]!=1)g++;
				if(vr[e.ry][e.rx]!=1)g++;
				vh[e.hy][e.hx]=1;
				vr[e.ry][e.rx]=1;
				q.push(e);
				if(b[0]==1)e.hx-=a[i];
				if(b[1]==1)e.rx+=a[i];
			}
		}
		e.tim--;
	}
	while(!q.empty())q.pop();
	if(e.tim>=100||g==(w*h-k)*2)printf("NA\n");
	else cout<<e.tim<<endl;
}
return 0;
}