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 ans <= now.Turn {
			continue
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = 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>
#include <algorithm>

#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
using namespace std;


bool table[55][55];

struct state{
	int tx;
	int ty;
	int kx;
	int ky;
	int t;
};

int x,y;
int tx,ty;
int kx,ky;

bool check(int cx,int dx,int cy,int dy){
	if(0<=cx+dx&&cx+dx<x&&0<=cy+dy&&cy+dy<y&&(!table[cx+dx][cy+dy]))
		return true;
	else
		return false;
}

bool visited[55][55][55][55];


int dx[4]={1,0,-1,0};
int dy[4]={0,-1,0,1};


int bfs(void){
	rep(i,55)rep(j,55)rep(k,55)rep(l,55) visited[i][j][k][l]=false;
	state init;
	init.tx=tx;init.ty=ty;
	init.kx=kx;init.ky=ky;
	init.t=0;
	queue<state> q;

	q.push(init);
	visited[init.tx][init.ty][init.kx][init.ky]=true;

	while(!q.empty()){
	//	cout << "check" << endl;
		state cur=q.front();q.pop();
		if(cur.tx==cur.kx&&cur.ty==cur.ky)
			return cur.t;

		if(cur.t>=100)
			continue;
	//	cout << "check" << endl;
		rep(i,4){
			state next=cur;
			if(check(cur.tx,dx[i],cur.ty,dy[i])){
				next.tx+=dx[i];
				next.ty+=dy[i];
			}
			if(check(cur.kx,dx[(i+2)%4],cur.ky,dy[(i+2)%4])){
				next.kx+=dx[(i+2)%4];
				next.ky+=dy[(i+2)%4];
			}
			next.t++;
			if(!visited[next.tx][next.ty][next.kx][next.ky]){
				visited[next.tx][next.ty][next.kx][next.ky]=true;
				q.push(next);
			}
		//	cout << next.tx << " " << next.ty << endl; 
		//	cout << "check" << endl;
		}
	}
	return -1;
}

int main(void){
	
	while(cin >> x >> y,x|y){
		
		cin >> tx >> ty;
		cin >> kx >> ky;
		tx--;ty--;kx--;ky--;
		rep(i,y)rep(j,x) cin >> table[j][i];
		int res=bfs();
		if(res==-1)
			cout << "NA" << endl;
		else
			cout << res << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int h,w;
int map[100][100];
int qtx[800000],qty[800000],qkx[800000],qky[800000];
int ql[800000];
int tail,head;
int ans;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
bool vis[60][60][60][60];
bool bend;
void BFS(int tx,int ty,int kx,int ky,int len){
	if(len==100)return;
	if(tx==kx&&ty==ky){
		ans=len;
		bend=true;
		return;
	}
	for(int i=0;i<4;i++){
		bool mt=false,mk=false;
		if(tx+dx[i]>=0&&tx+dx[i]<w&&ty+dy[i]>=0&&ty+dy[i]<h){
			if(map[ty+dy[i]][tx+dx[i]]==0){
				mt=true;
			}
		}
		if(kx-dx[i]>=0&&kx-dx[i]<w&&ky-dy[i]>=0&&ky-dy[i]<h){
			if(map[ky-dy[i]][kx-dx[i]]==0){
				mk=true;
			}
		}
		qtx[tail]=tx+mt*dx[i],qty[tail]=ty+mt*dy[i];
		qkx[tail]=kx-mk*dx[i],qky[tail]=ky-mk*dy[i];
		ql[tail]=len+1;
		tail++;
	}
}
int main(){
	while(true){
	cin>>w>>h;
	if(w==0&&h==0)break;
	for(int i=0;i<60;i++){
		for(int j=0;j<60;j++){
			for(int k=0;k<60;k++){
				for(int r=0;r<60;r++){
					vis[i][j][k][r]=false;
				}
			}
		}
	}
	int tx,ty,kx,ky;
	cin>>tx>>ty>>kx>>ky;
	tx--,ty--,kx--,ky--;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			cin>>map[i][j];
		}
	}
	ans=869121;
	qtx[0]=tx,qty[0]=ty,qkx[0]=kx,qky[0]=ky;
	ql[0]=0;
	tail=1,head=0;
	bend=false;
	while(true){
		if(tail==head)break;
		if(!vis[qtx[head]][qty[head]][qkx[head]][qky[head]]){
		vis[qtx[head]][qty[head]][qkx[head]][qky[head]]=true;
		BFS(qtx[head],qty[head],qkx[head],qky[head],ql[head]);
		}
		if(bend)break;
		head++;
	}
	if(ans==869121)cout<<"NA"<<endl;
	else cout<<ans<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
struct maigo{
	int x[2];// ????????????[0]???????????????[1]
	int y[2];// ????????????[0]???????????????[1]
	int count;
};
int main(){
	queue<maigo> q;
	int tx, ty; int kx, ky;
	int **depart, X, Y;
	int flag = 0, a = 0;
	cin >> X >> Y;
	while (X != 0 && Y != 0){
		depart = new int*[Y + 2];
		for (int i = 0; i < Y + 2; i++){
			depart[i] = new int[X + 2];
		}
		for (int i = 0; i < Y + 2; i++){
			for (int l = 0; l < X + 2; l++){
				depart[i][l] = 3;
			}
		}
		cin >> tx >> ty;
		cin >> kx >> ky;
		for (int i = 1; i < Y + 1; i++){
			for (int l = 1; l < X + 1; l++){
				cin >> depart[i][l];
			}
		}
		maigo temp;
		temp.x[0] = tx; temp.y[0] = ty;
		temp.x[1] = kx; temp.y[1] = ky;
		temp.count = 1;
		q.push(temp);
		while (!q.empty() && flag == 0){
			maigo t = q.front();
			q.pop();
			int dx1[4] = { 1, 0, -1, 0 }; int dx2[4] = { 0, 1, 0, -1 };
			for (int i = 0; i < 4; i++){
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 &&
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] = -1;
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] = -1;
					if (t.x[0] + dx1[i] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] + dx2[i] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					maigo into;
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);
					into.count = t.count + 1;
					if (into.count >= 100){
						flag = 1;
						a = 1;
					}
					q.push(into);
				}
			}
		}if (a == 1||flag == 0) {
			cout << "NA" << endl;
		}while (!q.empty()) q.pop();
		a = 0; flag = 0;
		cin >> X >> Y;
	}
	return 0;
}