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 <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";
		}
	}
}

C++: #include<stdio.h>
#define QUEUE_MAX 1000
typedef struct {
    int x;
	int y;
} queue_t;
queue_t t[QUEUE_MAX],k[QUEUE_MAX];
int thead=0,khead=0,tnum=0,knum=0;
int tpush( int vx, int vy ) {
	if(thead+tnum<QUEUE_MAX){
		t[thead+tnum].x=vx;
		t[thead+tnum].y=vy;
		tnum++;
		return 0;
	}
}
int tpop( int *vx, int *vy ) {
	if( tnum > 0 ){
		*vx = t[thead].x;
		*vy = t[thead].y;
		tnum--;
		thead++;
		return 0;
	}
}
int kpush( int vx, int vy ) {
	if(khead+knum<QUEUE_MAX){
		k[khead+knum].x=vx;
		k[khead+knum].y=vy;
		knum++;
		return 0;
	}
}
int kpop( int *vx, int *vy ) {
	if( knum > 0 ){
		*vx = k[khead].x;
		*vy = k[khead].y;
		knum--;
		khead++;
		return 0;
	}
}
int main(){
	while(1){
		int x,y,d[50][50],i,j,tlx[4]={0,1,0,-1},tly[4]={-1,0,1,0},cnt=0,tfx,tfy,kfx,kfy,klx[4]={0,-1,0,1},kly[4]={1,0,-1,0},tc[50][50]={},kc[50][50]={},tm[50][50]={},km[50][50]={},mx,my,f=0,h[50][50]={};
		thead=0;
		khead=0;
		tnum=0;
		knum=0;
		for(i=0;i<QUEUE_MAX;i++){
			t[i].x=0;
			t[i].y=0;
			k[i].x=0;
			k[i].y=0;
		}
		scanf("%d %d",&mx,&my);
			if(mx==0&&my==0){
				break;
			}
		scanf("%d %d",&tfx,&tfy);
		scanf("%d %d",&kfx,&kfy);
		tpush(tfx-1,tfy-1);
		kpush(kfx-1,kfy-1);
		for(i=0;i<my;i++){
			for(j=0;j<mx;j++){
					scanf("%d",&d[i][j]);
			}
		}
		while(1){
			while(1){
				tpop(&tfx,&tfy);
				kpop(&kfx,&kfy);
				if(tfx!=1000&&tfy!=1000&&kfx!=1000&&kfy!=1000){
					break;
				}
			}
			if(tfx==kfx&&tfy==kfy){
				break;
			}
			tm[tfy][tfx]=1;
			km[kfy][kfx]=1;
			for(i=0;i<4;i++){
				if(d[tfy+tly[i]][tfx+tlx[i]]==0&&tm[tfy+tly[i]][tfx+tlx[i]]==0&&(tfx+tlx[i])>=0&&(tfx+tlx[i])<mx&&(tfy+tly[i])>=0&&(tfy+tly[i])<my){
					tpush(tfx+tlx[i],tfy+tly[i]);
					tc[tfy+tly[i]][tfx+tlx[i]]=tc[tfy][tfx]+1;
					h[tfy+tly[i]][tfx+tlx[i]]=1;
				}
				else{
					tpush(1000,1000);
				}
				if(d[kfy+kly[i]][kfx+klx[i]]==0&&km[kfy+kly[i]][kfx+klx[i]]==0&&(kfx+klx[i])>=0&&(kfx+klx[i])<mx&&(kfy+kly[i])>=0&&(kfy+kly[i])<my){
					kpush(kfx+klx[i],kfy+kly[i]);
					kc[kfy+kly[i]][kfx+klx[i]]=kc[kfy][kfx]+1;
					h[kfy+kly[i]][kfx+klx[i]]=1;
				}
				else{
					kpush(1000,1000);
				}
			}
			f=0;
			for(i=0;i<my;i++){
				for(j=0;j<mx;j++){
					if(d[i][j]==0&&h[i][j]==0){
						f=1;
					}
				}
			}
			if(f==0){
				break;
			}
		}
		if(tfx==kfx&&tfy==kfy){
				printf("%d\n",tc[tfy][tfx]);
		}
		else{
			printf("NA\n");
		}
	}
	return 0;
}