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 := &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++
			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 <queue>

using namespace std;
struct PointPair {
        int step;
        int tx, ty, kx, ky;
};

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

bool passed[50][50][50][50];
bool field[50][50];

int main(){
        while(true){
                memset(passed, 0, sizeof(passed));
                memset(field, 0, sizeof(field));
                int X, Y, tx, ty, kx, ky;
                cin >> X >> Y;
                if(X == 0 || Y == 0){ break; }
                cin >> tx >> ty >> kx >> ky;
                for(int i = 0; i < Y; ++i){
                        for(int j = 0; j < X; ++j){
                                int f;
                                cin >> f;
                                field[i][j] = (f != 0);
                        }
                }
                --tx; --ty; --kx; --ky;
                PointPair init = { 0, tx, ty, kx, ky };
                queue<PointPair> q;
                q.push(init);
                passed[tx][ty][kx][ky] = true;
                int answer = -1;
                while(!q.empty()){
                        PointPair p = q.front();
                        if(p.step >= 100){ break; }
                        if(p.tx == p.kx && p.ty == p.ky){
                                answer = p.step;
                                break;
                        }
                        q.pop();
                        for(int i = 0; i < 4; ++i){
                                PointPair next;
                                next.step = p.step + 1;
                                next.tx = p.tx + dx[i];
                                next.ty = p.ty + dy[i];
                                if(field[next.tx][next.ty]){
                                        next.tx = p.tx;
                                        next.ty = p.ty;
                                }else{
                                        if(next.tx < 0){ next.tx = 0; }
                                        if(next.tx >= X){ next.tx = X - 1; }
                                        if(next.ty < 0){ next.ty = 0; }
                                        if(next.ty >= Y){ next.ty = Y - 1; }
                                }
                                next.kx = p.kx - dx[i];
                                next.ky = p.ky - dy[i];
                                if(field[next.kx][next.ky]){
                                        next.kx = p.kx;
                                        next.ky = p.ky;
                                }else{
                                        if(next.kx < 0){ next.kx = 0; }
                                        if(next.kx >= X){ next.kx = X - 1; }
                                        if(next.ky < 0){ next.ky = 0; }
                                        if(next.ky >= Y){ next.ky = Y - 1; }
                                }
                                if(!passed[next.tx][next.ty][next.kx][next.ky]){
                                        passed[next.tx][next.ty][next.kx][next.ky] = true;
                                        q.push(next);
                                }
                        }
                }
                if(answer < 0){
                        cout << "NA" << endl;
                }else{
                        cout << answer << endl;
                }
        }
        return 0;
}

C++: #include<stdio.h>

#include<queue>
#include<iostream>
#include<string.h>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[52][52][52][52];
int main(){
	PP S;
	queue<PP> P;
	int  w,h;
	int d=0,i=0,j=0,l=-1,D[54][54];
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&w,&h);
	while(w!=0||h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1;
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			printf("%d\n",S.Z);
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;

		if(D[S.ty][S.tx]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.ky][S.kx]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	}
	while(!P.empty()){
	P.pop();
	}
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;
}