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 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)
	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 len(pq) > 0 {
		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++
			if next.Turn <= 100 {
				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 <vector>
#include <algorithm>
#include <string>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
 
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define all(v) (v).begin(), (v).end()
#define rev(s) (s).rbegin(), (s).rend()
#define MP make_pair
#define X first
#define Y second
 
using namespace std;
 
typedef long long ll;
typedef pair<int, int> P;

int field[50][50];
int visit[50][50][50][50];

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

int w, h;

bool canmove(int x, int y){
	if(x < 0 || x >= w || y < 0 || y >= h) return false;
	if(field[y][x]) return false;
	return true;
}

int main(){

	while(cin >> w >> h, w|h){
		int tx, ty, kx, ky;
		cin >> tx >> ty >> kx >> ky;
		rep(i, h) rep(j, w) cin >> field[i][j];

		memset(visit, 0, sizeof(visit));

		queue<pair<pair<P, P>, int> > q;
		q.push(MP(MP(MP(tx, ty), MP(kx, ky)), 0));

		int ans = -1;
		while(!q.empty()){
			P t, k;
			t = q.front().first.first;
			k = q.front().first.second;
			int time = q.front().second;
			q.pop();

			if(visit[t.X][t.Y][k.X][k.Y]) continue;
			visit[t.X][t.Y][k.X][k.Y] = 1;

			if(t == k){
				ans = time;
				break;
			}

			rep(i, 4){
				int ntx = t.X + dx[i];
				int nty = t.Y + dy[i];
				int nkx = k.X - dx[i];
				int nky = k.Y - dy[i];
				if(!canmove(ntx, nty)) ntx = t.X, nty = t.Y;
				if(!canmove(nkx, nky)) nkx = k.X, nky = k.Y;
				q.push(MP(MP(MP(ntx, nty), MP(nkx, nky)), time+1));
			}
		}

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


	return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;

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

struct State { int tx, ty, kx, ky, cost; };
int X, Y;
int d[52][52];
bool used[52][52][52][52];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    while (cin >> X >> Y, X) {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        for (int i=0; i<=Y+1; ++i) {
            for (int j=0; j<=X+1; ++j) {
                if (i==0 || i==Y+1 || j==0 || j==X+1) d[i][j] = 1;
                else cin >> d[i][j];
            }
        }
        memset(used, false, sizeof used);
        queue<State> q;
        q.push((State){tx, ty, kx, ky, 0});
        int res = -1;
        while ( ! q.empty()) {
            State s = q.front(); q.pop();
            if (used[s.tx][s.ty][s.kx][s.ky]) continue;
            used[s.tx][s.ty][s.kx][s.ky] = true;
            if (s.tx == s.kx && s.ty == s.ky) {
                res = s.cost;
                break;
            }
            for (int i=0; i<4; ++i) {
                if (d[s.ty+dy[i]][s.tx+dx[i]] && d[s.ky-dy[i]][s.kx-dx[i]]) continue;
                int tx2 = s.tx, ty2 = s.ty;
                if ( ! d[s.ty+dy[i]][s.tx+dx[i]]) {
                    tx2 += dx[i];
                    ty2 += dy[i];
                }
                int kx2 = s.kx, ky2 = s.ky;
                if ( ! d[s.ky-dy[i]][s.kx-dx[i]]) {
                    kx2 -= dx[i];
                    ky2 -= dy[i];
                }
                q.push((State){tx2, ty2, kx2, ky2, s.cost+1});
            }
        }
        if (res < 0) {
            cout << "NA" << endl;
        } else {
            cout << res << endl;
        }
    }
    return 0;
}

C++: #include<queue>
#include<stdio.h>

using namespace std;

class T{
	public:
	int x1,x2,y1,y2,count;
	T(int x1,int y1,int x2,int y2,int count):x1(x1),y1(y1),x2(x2),y2(y2),count(count){}
};

char check[55][55][55][55];
int board[55][55];

int main(){
	while(1){
		for(int i=0;i<55;i++){
			for(int j=0;j<55;j++){
				for(int k=0;k<55;k++){
					for(int p=0;p<55;p++)check[i][j][k][p]=0;
				}
			}
		}
		
		int w,h;
		int sx1,sx2,sy1,sy2;
		
		scanf("%d%d",&w,&h);
		if(w==0 && h==0)break;
		
		scanf("%d%d%d%d",&sx1,&sy1,&sx2,&sy2);
		
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				scanf("%d",&board[i][j]);
			}
		}
		
		
		queue<T> que;
		que.push(T(sx1,sy1,sx2,sy2,0));
		
		while(1){
			if(que.empty())break;
			
			T u = que.front();
			que.pop();
			
			if(check[u.x1][u.y1][u.x2][u.y2]==1)continue;
			check[u.x1][u.y1][u.x2][u.y2]=1;
			
			if(u.x1 == u.x2 && u.y1 == u.y2){
				printf("%d\n",u.count);
				goto A;
			}
			
			int dx[4] = {0,1,0,-1};
			int dy[4] = {1,0,-1,0};
			for(int i=0;i<4;i++){
				int nx1 = u.x1 + dx[i];
				int ny1 = u.y1 + dy[i];
				
				int nx2 = u.x2 - dx[i];
				int ny2 = u.y2 - dy[i];
				
				if(nx1<0 || ny1<0 || nx1>=w || ny1>=h || board[ny1][nx1]==1){
					nx1=u.x1;
					ny1=u.y1;
				}
				if(nx2<0 || ny2<0 || nx2>=w || ny2>=h || board[ny2][nx2]==1){
					nx2=u.x2;
					ny2=u.y2;
				}
				que.push(T(nx1,ny1,nx2,ny2,u.count+1));
			}
		}
		
		printf("NA\n");
		A:;
	}
}