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 <vector>
#include <queue>
#include <cstring>

using namespace std;
const int INF = 99999999;
typedef pair<int, int> P;
typedef pair<P, P> PP;
typedef pair<PP, int> PPP;
vector< vector<char> > Field;
bool used1[51][51];
bool used2[51][51];
int dx1[] = {-1,  0,  0,  1};
int dy1[] = { 0, -1,  1,  0};
int dx2[] = { 1,  0,  0, -1};
int dy2[] = { 0,  1, -1,  0};

void solve()
{
	int x, y;
	while(cin >> x >> y, x || y)
	{
		memset(used1, 0, sizeof(used1));
		memset(used2, 0, sizeof(used2));
		P t, k;
		cin >> t.first >> t.second >> k.first >> k.second;
		Field.resize(y + 2);
		for(int i = 0; i < y + 2; ++i)
		{
			Field[i].resize(x + 2);
			for(int j = 0; j < x + 2; ++j)
			{
				Field[i][j] = '1';
			}
		}
		for(int i = 1; i <= y; ++i)
		{
			for(int j = 1; j <= x; ++j)
			{
				cin >> Field[i][j];
			}
		}
		queue<PPP> Que;
		PPP ppp;
		ppp.first.first = t;
		ppp.first.second = k;
		ppp.second = 0;
		int count = 0;
		Que.push(ppp);
		while(!Que.empty())
		{
			PPP front = Que.front();
			Que.pop();
			if(front.second >= 100)
			{
				break;
			}
			if(front.first.first.first == front.first.second.first && front.first.first.second == front.first.second.second)
			{
				cout << front.second << endl;
				goto NEXT;
			}
			used1[front.first.first.second][front.first.first.first] = true;
			used2[front.first.second.second][front.first.second.first] = true;
			for(int i = 0; i < 4; ++i)
			{
				int nx1 = front.first.first.first + dx1[i];
				int ny1 = front.first.first.second + dy1[i];
				int nx2 = front.first.second.first + dx2[i];
				int ny2 = front.first.second.second + dy2[i];
				if(Field[ny1][nx1] == '0' && Field[ny2][nx2] == '0' && !used1[ny1][nx1] && !used2[ny2][nx2])
				{
					PPP next;
					next.first.first.first = nx1;
					next.first.first.second = ny1;
					next.first.second.first = nx2;
					next.first.second.second = ny2;
					next.second = front.second + 1;
					Que.push(next);
				}
				else if(Field[ny1][nx1] == '1' && Field[ny2][nx2] == '0' && !used2[ny2][nx2])
				{
					PPP next;
					next.first.first.first = front.first.first.first;
					next.first.first.second = front.first.first.second;
					next.first.second.first = nx2;
					next.first.second.second = ny2;
					next.second = front.second + 1;
					Que.push(next);
				}
				else if(Field[ny1][nx1] == '0' && Field[ny2][nx2] == '1' && !used1[ny1][nx1])
				{
					PPP next;
					next.first.first.first = nx1;
					next.first.first.second = ny1;
					next.first.second.first = front.first.second.first;
					next.first.second.second = front.first.second.second;
					next.second = front.second + 1;
					Que.push(next);
				}
			}
		}
		cout << "NA" << endl;
NEXT:
		;
	}
}

int main()
{
	solve();
	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;
}