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 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<cstdio>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<queue>
#include<string.h>
#include<string>
#include<vector>
using namespace std;
struct X
{
	int tx, ty, t, kx, ky;
};
static int java[51][51][51][51];
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
int main()
{
	while (1)
	{
		int w, h, map[52][52];
		int mx[] = { 0,1,0,-1 }, my[] = { 1,0,-1,0 };
		queue<X> que;
		X c;
		cin >> w >> h;
		if (w == 0 && h == 0)
			break;
		memset(java, 0, sizeof(java));
		cin >> c.tx >> c.ty >> c.kx >> c.ky;
		c.t = 0;
		que.push(c);
		rep1(i, h)
		{
			rep(j, w)
			{
				cin >> map[i][j];
			}
		}
		/*?£???????*/
		rep(i, h + 2)	//n???????????°,m????¨??????°
		{
			map[i][0] = 1;
			map[i][w + 1] = 1;
		}
		rep(i, w + 2)
		{
			map[0][i] = 1;
			map[h + 1][i] = 1;
		}
		while (1)
		{
			c = que.front();
			que.pop();
			java[c.tx][c.ty][c.kx][c.ky] = 1;
			if (c.tx == c.kx&&c.ty == c.ky&&c.t >= 100)
			{
				break;
			}
			c.t++;
			rep(i, 4)
			{
				if (java[c.tx + mx[i]][c.ty + my[i]][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
				{
					c.tx += mx[i];
					c.ty += my[i];
					c.kx -= mx[i];
					c.ky -= my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.tx -= mx[i];
					c.ty -= my[i];
					c.kx += mx[i];
					c.ky += my[i];
				}
				if (java[c.tx][c.ty][c.kx - mx[i]][c.ky - my[i]] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 1 && map[c.kx - mx[i]][c.ky - my[i]] == 0)
				{
					c.kx -= mx[i];
					c.ky -= my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.kx += mx[i];
					c.ky += my[i];
				}
				if (java[c.tx + mx[i]][c.ty + my[i]][c.kx][c.ky] == 0 && map[c.tx + mx[i]][c.ty + my[i]] == 0 && map[c.kx - mx[i]][c.ky - my[i]] == 1)
				{
					c.tx += mx[i];
					c.ty += my[i];
					que.push(c);
					java[c.tx][c.ty][c.kx][c.ky] = 1;
					c.tx -= mx[i];
					c.ty -= my[i];
				}
			}
		}
		if (c.t < 100)
			cout << c.t << endl;
		else
			cout << "NA" << endl;
	}
	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(a) (a).begin(),(a).end()
#define pb emplace_back
#define INF (1e9+1)

int w,h;
int v[51][51];

struct Pos{
    int ay,ax,by,bx;
    
    bool operator < (Pos obj) const{
        int t = ay + ax*60 + by*60*60 + bx*60*60*60;
        int p = obj.ay + obj.ax*60 + obj.by*60*60 + obj.bx*60*60*60;
        return t<p;
    }
    
};

int main(){
    while(cin>>w>>h&&(w||h)){
        int ax,ay,bx,by;
        cin>>ax>>ay>>bx>>by;
        ax--,ay--,bx--,by--;
        
        rep(i,h)rep(j,w)cin>>v[i][j];
        
        int dy[]={1,0,-1,0};
        int dx[]={0,1,0,-1};
        
        map<Pos,int> mp;
        queue<Pos> que;
        
        mp[Pos{ay,ax,by,bx}] = 0;
        que.push( Pos{ay,ax,by,bx} );
        
        while(que.size()){
            Pos q = que.front();
            int iy = q.ay, ix = q.ax;
            int jy = q.by, jx = q.bx;
            
            rep(k,4){
                int ddix = ix+dx[k];
                int ddjx = jx-dx[k];
                int ddiy = iy+dy[k];
                int ddjy = jy-dy[k];
                
                if(ddiy<0 || ddiy>=h || ddix<0 || ddix>=w || v[ddiy][ddix])ddiy = iy, ddix = ix;
                if(ddjy<0 || ddjy>=h || ddjx<0 || ddjx>=w || v[ddjy][ddjx])ddjy = jy, ddjx = jx;
                
                if( mp.count( Pos{ddiy, ddix, ddjy, ddjx} )==0 || mp[Pos{ddiy, ddix, ddjy, ddjx}]>mp[Pos{iy, ix, jy, jx}]+1 ){
                    que.push( Pos{ddiy, ddix, ddjy, ddjx} );
                    mp[Pos{ddiy, ddix, ddjy, ddjx}] = mp[Pos{iy, ix, jy, jx}]+1;
                }
            }
            que.pop();
        }
        
        int ans = INF;
        rep(i,h){
            rep(j,w){
                if(mp.count(Pos{i,j,i,j})==0)continue;
                ans = min(ans,mp[Pos{i,j,i,j}]);
            }
        }
        if(ans>=100)cout<<"NA"<<endl;
        else cout<<ans<<endl;
    }
}