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 <iostream>
#include <queue>
#include <string.h>
using namespace std;
struct data{
    int x=0,y=0,turn=0;
};
data t,s;
queue <data> q,er;
int main(void){
    int w,h,tx,ty,kx,ky,d[51][51];
    cin>>w>>h;
    while(w!=0||h!=0){
        cin>>tx>>ty>>kx>>ky;
        t.x=tx;
        t.y=ty;
        t.turn=0;
        q.push(t);
        s.x=kx;
        s.y=ky;
        s.turn=0;
        er.push(s);
        for(int i=1;i<=h;i++){
            for(int p=1;p<=w;p++){
                cin>>d[i][p];
            }
        }
        int fx,ax,mx[]={0,1,0,-1},rx[]={0,-1,0,1};
        int fy,ay,my[]={1,0,-1,0},ry[]={-1,0,1,0};
        int te,se,cnt=0;
        while (1){
            /*cnt++;
            cout<<cnt<<' '<<t.turn<<endl;*/
            t=q.front();
            ty=t.y;
            tx=t.x;
            te=t.turn;
            s=er.front();
            ky=s.y;
            kx=s.x;
            se=s.turn;
            q.pop();
            er.pop();/*
            for(int i=1;i<=h;i++){
                for(int p=1;p<=w;p++){
                    if(i==t.y&&p==t.x){
                        cout<<"t ";
                    }
                    else if(i==s.y&&p==s.x){
                        cout<<"s ";
                    }
                    else{
                        cout<<d[i][p]<<' ';
                    }
                }
                cout<<endl;
            }
            cout<<endl<<endl;*/
            if(t.y==s.y&&t.x==s.x){
                cout<<t.turn<<endl;
                break;
            }
            if(t.turn>=100){
                cout<<"NA"<<endl;
                break;
            }
            for(int i=0;i<4;i++){
                fx=tx+mx[i];
                fy=ty+my[i];
                ax=kx+rx[i];
                ay=ky+ry[i];
                if(d[fy][fx]==0&&ax>0&&ax<=w&&ay>0&&ay<=h){
                    t.y=fy;
                    t.x=fx;
                    t.turn=te+1;
                    q.push(t);
                }
                else if(d[fy][fx]==1||fx<=0||fx>w||fy<=0||fy>h){
                    t.turn=te+1;
                    q.push(t);
                }
                if(d[ay][ax]==0&&ax>0&&ax<=w&&ay>0&&ay<=h){
                    s.y=ay;
                    s.x=ax;
                    s.turn=se+1;
                    er.push(s);
                }
                else if(d[ay][ax]==1||ax<=0||ax>w||ay<=0||ay>h){
                    s.turn=se+1;
                    er.push(s);
                }
            }
        }
        while(!q.empty()){
            q.pop();
        }
        while(!er.empty()){
            er.pop();
        }
        cnt=0;
        memset(d,0,sizeof(d));
        cin>>w>>h;
    }
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <string.h>

using namespace std;
static const int dx[] = {1, 0, -1, 0};
static const int dy[] = {0, -1, 0, 1};
bool isVisited[51][51][51][51];

class point
{
public:
	int tx, ty;
	int kx, ky;
};

class data
{
public:
	point p;
	int cnt;
};

void solve()
{
	int X, Y;
	while (cin >> X >> Y, X || Y)
	{
		data d;
		cin >> d.p.tx >> d.p.ty >> d.p.kx >> d.p.ky;
		--d.p.tx; --d.p.ty;
		--d.p.kx; --d.p.ky;
		d.cnt = 0;
		vector< vector<char> > field(Y, vector<char>(X));
		for (int i = 0; i < Y; ++i)
		{
			for (int j = 0; j < X; ++j)
			{
				cin >> field[i][j];
			}
		}
		memset(isVisited, 0, sizeof(isVisited));
		queue<data> Que;
		Que.push(d);
		isVisited[d.p.ty][d.p.tx][d.p.ky][d.p.kx] = true;
		bool findFlag = false;
		while (!Que.empty())
		{
			data cur = Que.front();
			Que.pop();
			if (cur.cnt >= 100)
			{
				break;
			}
			if (cur.p.tx == cur.p.kx && cur.p.ty == cur.p.ky)
			{
				cout << cur.cnt << endl;
				findFlag = true;
				break;
			}
			for (int i = 0; i < 4; ++i)
			{
				data next;
				next.p.tx = cur.p.tx + dx[i];
				next.p.ty = cur.p.ty + dy[i];
				if (!(0 <= next.p.tx && next.p.tx < X && 0 <= next.p.ty && next.p.ty < Y) || field[next.p.ty][next.p.tx] == '1')
				{
					next.p.tx = cur.p.tx;
					next.p.ty = cur.p.ty;
				}
				next.p.kx = cur.p.kx + dx[(i + 2) % 4];
				next.p.ky = cur.p.ky + dy[(i + 2) % 4];
				if (!(0 <= next.p.kx && next.p.kx < X && 0 <= next.p.ky && next.p.ky < Y) || field[next.p.ky][next.p.kx] == '1')
				{
					next.p.kx = cur.p.kx;
					next.p.ky = cur.p.ky;
				}
				next.cnt = cur.cnt + 1;
				if (isVisited[next.p.ty][next.p.tx][next.p.ky][next.p.kx] == false)
				{
					Que.push(next);
					isVisited[next.p.ty][next.p.tx][next.p.ky][next.p.kx] = true;
				}
			}
		}
		if (!findFlag)
		{
			cout << "NA" << endl;
		}
	}
}

int main()
{
	solve();
	return(0);
}