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<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<queue>
#include<iostream>
using namespace std;
struct data{
    int x;
    int y;
    int u;
    int v;
    int t;
};

bool vis[60][60][60][60] = {};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
int main(void){
    int w,h;
    while(cin>>w>>h,w){
        int x,y,u,v;
        cin>>x>>y>>u>>v;
        bool screen[60][60] = {};
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin>>screen[i][j];
            }
        }
        data D;
        D.x = x,D.y = y;
        D.u = u,D.v = v;
        D.t = 0;
        queue<data> Q;
        Q.push(D);

        while(!Q.empty()){
            data E = Q.front();Q.pop();

            if(E.x == E.u&&E.y == E.v){
                cout<<E.t<<endl;
                goto e;
            }
            if(E.t>99)break;
            for(int i = 0;i < 4;i++){

                    data F = E;
                    F.t++;
                    F.x+=dx[i],F.y+=dy[i],F.u+=dx[(i+2)%4],F.v+=dy[(i+2)%4];
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h)){
                        F.x = E.x,F.y = E.y;
                    }
                    if(screen[F.x][F.y])F.x = E.x,F.y = E.y;
                    if(!(0<=F.u&&F.u<w&&0<=F.v&&F.v<h)){
                        F.u = E.u,F.v = E.v;
                    }
                    if(screen[F.u][F.v])F.u = E.u,F.v = E.v;
                    if(vis[F.x][F.y][F.u][F.v]||vis[F.u][F.v][F.x][F.y])continue;

                    vis[F.x][F.y][F.u][F.v] = true;
                    vis[F.u][F.v][F.x][F.y] = true;
                    Q.push(F);

            }

        }
        cout<<"NA"<<endl;
        e:;
    }


    return 0;
}

C++: #include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <map>
#include <sstream>
#include <queue>
#include <cstdlib>
#include <algorithm>
#include <iterator>
#include <stack>
#include <list>
using namespace std;

#define INF 100000000
typedef long long int lli;
typedef pair<int,int> P;
struct cost{
	P tp,kp;
	int cnt;
};
int MAP[51][51];
int dt[51][51];
int dk[51][51];
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
bool passed[51][51][51][51];

string IntToString(int number){
	stringstream ss;
	ss << number;
	return ss.str();
}

int main(){
	int X,Y;
	while(cin>>X>>Y&&X&&Y){
		int tx,ty,kx,ky;
		cin >> tx >> ty >> kx >> ky;
		for(int i=1; i<=Y; ++i){
			for(int j=1; j<=X; ++j){
				cin >> MAP[j][i];
			}
		}
		for(int i=1;i<=X; ++i){
			for(int j=1; j<=Y; ++j){
				for(int k=1; k<=X; ++k){
					for(int l=1; l<=Y; ++l){
						passed[i][j][k][l]=false;
					}
				}
			}
		}
		cost ans;
		queue<cost> q;
		cost c;
		c.cnt=0;
		c.tp=P(tx,ty);
		c.kp=P(kx,ky);
		q.push(c);
		bool flag=false;
		while(q.size()){
			cost now = q.front();
			q.pop();
			if(now.cnt>=100){
				break;
			}
			if(now.tp.first==now.kp.first&&now.kp.second==now.tp.second){
				ans=now;
				flag=true;
				break;
			}
			for(int i=0; i<4; ++i){
				cost np;
				np.cnt=now.cnt+1;
				if(1<=now.tp.first+dx[i]&&now.tp.first+dx[i]<=X&&MAP[now.tp.first+dx[i]][now.tp.second]!=1){
					np.tp.first=now.tp.first+dx[i];
				} else {
					np.tp.first=now.tp.first;
				}
				if(1<=now.tp.second+dy[i]&&now.tp.second+dy[i]<=Y&&MAP[now.tp.first][now.tp.second+dy[i]]!=1){
					np.tp.second=now.tp.second+dy[i];
				} else {
					np.tp.second=now.tp.second;
				}
				if(1<=now.kp.first-dx[i]&&now.kp.first-dx[i]<=X&&MAP[now.kp.first-dx[i]][now.kp.second]!=1){
					np.kp.first=now.kp.first-dx[i];
				} else {
					np.kp.first=now.kp.first;
				}
				if(1<=now.kp.second-dy[i]&&now.kp.second-dy[i]<=Y&&MAP[now.kp.first][now.kp.second-dy[i]]!=1){
					np.kp.second=now.kp.second-dy[i];
				} else {
					np.kp.second=now.kp.second;
				}
				if(!passed[np.tp.first][np.tp.second][np.kp.first][np.kp.second]){
					q.push(np);
					passed[np.tp.first][np.tp.second][np.kp.first][np.kp.second]=true;
				}
			}
		}
		if(flag){
			cout << ans.cnt << "\n";
		} else {
			cout << "NA\n";
		}
	}
}