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 <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define INF INT_MAX/3
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define CLR(a) memset(a,0,sizeof(a))

typedef long long int ll;

using namespace std;
int dx[] = {-1,0,0,1};
int dy[] = {0,1,-1,0};
int xs,ys,tx,ty,kx,ky;


int main(){
    while(true){
	cin >> xs >> ys;
	if(xs == 0 && ys == 0) break;
	cin >> tx >> ty;
	cin >> kx >> ky;
	tx--;
	ty--;
	kx--;
	ky--;
	vector< vector<int> > map(ys,vector<int>(xs));
	REP(i,ys)REP(j,xs) cin >> map[i][j];

	queue<int> qtx;
	queue<int> qty;
	queue<int> qkx;
	queue<int> qky;
	queue<int> qn;
	vector< vector<bool> > tu(ys,vector<bool>(xs,false));
	vector< vector<bool> > ku(ys,vector<bool>(xs,false));
	int t,k;
	int ans = 10000000;
	qtx.push(tx);
	qty.push(ty);
	qkx.push(kx);
	qky.push(ky);
	qn.push(1);
	while(!qtx.empty()){
	    int x1 = qtx.front();
	    int y1 = qty.front();
	    int x2 = qkx.front();
	    int y2 = qky.front();
	    int n = qn.front();
	    if(n >= 100){
		ans = 100;
		continue;
	    }
	    qtx.pop();
	    qty.pop();
	    qkx.pop();
	    qky.pop();
	    qn.pop();
	    REP(i,4){
		int ntx = x1 + dx[i];
		int nty = y1 + dy[i];
		int nkx = x2 - dx[i];
		int nky = y2 - dy[i];
		if(ntx<0 || xs <= ntx) ntx = x1;
		if(nty<0 || ys <= nty) nty = y1;
		if(nkx<0 || xs <= nkx) nkx = x2;
		if(nky<0 || ys <= nky) nky = y2;
		if(map[nty][ntx] == 1) {
		    ntx = x1;
		    nty = y1;
		}
		if(map[nky][nkx] == 1) {
		    nkx = x2;
		    nky = y2;
		}
		if(tu[nty][ntx] && ku[nky][nkx]) continue;
		tu[nty][ntx] = true;
		ku[nky][nkx] = true;
		if(ntx==nkx&&nty==nky){
		    ans = min(ans,n);
		}
		qtx.push(ntx);
		qty.push(nty);
		qkx.push(nkx);
		qky.push(nky);
		qn.push(n+1);
	    }
	}
	if(ans>=100) cout << "NA" << endl;
	else cout << ans << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<queue>

using namespace std ;

struct ST
{
	int tx ,ty ;
	int kx ,ky ;
	int cnt ;
	ST( int a ,int s ,int d ,int f ,int g ) : tx( a ) ,ty( s ) ,kx( d ) ,ky( f ) ,cnt( g ){}
} ;

int mx[ 4 ] = { 1 ,0 ,0 ,-1 } ;
int my[ 4 ] = { 0 ,1 ,-1 ,0 } ;
int map[ 50 ][ 50 ] ;

int w ,h ;
int tx ,kx ;
int ty ,ky ;

void ans()
{
	queue< ST > que ;
	bool came[ 50 ][ 50 ][ 50 ][ 50 ] = { false } ;
	que.push( ST( tx - 1 ,ty - 1 ,kx - 1 ,ky - 1 ,0 ) ) ;
	came[ tx - 1 ][ ty - 1 ][ kx - 1 ][ ky - 1 ] = true ;
	while( ! que.empty() )
	{
		ST st = que.front() ;
		if( st.tx == st.kx && st.ty == st.ky )
		{
			cout << st.cnt << endl ;
			return ;
		}
		else if( st.cnt >= 100 )
		{
			break ;
		}
		que.pop() ;
		for( int i = 0 ; i < 4 ; i++ )
		{
			int j = 3 - i ;
			tx = st.tx + mx[ i ] ;
			kx = st.kx + mx[ j ] ;
			ty = st.ty + my[ i ] ;
			ky = st.ky + my[ j ] ;
			if( tx < 0 || tx >= w || ty < 0 || ty >= h || map[ ty ][ tx ] )
			{
				tx = st.tx ;
				ty = st.ty ;
			}
			if( kx < 0 || kx >= w || ky < 0 || ky >= h || map[ ky ][ kx ] )
			{
				kx = st.kx ;
				ky = st.ky ;
			}
			if( came[ tx ][ ty ][ kx ][ ky ] == false )
			{
				que.push( ST( tx ,ty ,kx ,ky ,st.cnt + 1 ) ) ;
				came[ tx ][ ty ][ kx ][ ky ] = true ;
			}
		}
	}
	cout << "NA" << endl ;
}

int main()
{
	while( cin >> w >> h ,h )
	{
		cin >> tx >> ty ;
		cin >> kx >> ky ;
		for( int i = 0 ; i < h ; i++ )
		{
			for( int j = 0 ; j < w ; j++ )
			{
				cin >> map[ i ][ j ] ;
			}
		}
		ans() ;
	}
}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
using namespace std;
static const double EPS = 1e-5;
typedef long long ll;
typedef pair<int,int> pi;
#define rep(i,n) for(int i=0;i<n;i++)


int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
bool past[50][50][50][50];
int d[50][50];
int x,y;
int tx,ty,kx,ky;


main(){
	while(cin>>x>>y,x){
		cin>>tx>>ty>>kx>>ky;
		--tx;--ty;--kx;--ky;
		rep(i,x)rep(j,y)cin>>d[i][j];
		memset(past,0,sizeof(past));

		past[tx][ty][kx][ky]=1;
		queue<pair<pair<pi,pi>,int> > state;
		state.push(make_pair(make_pair(make_pair(tx,ty),make_pair(kx,ky)),0));
		
		
		bool na=true;
		
		while(!state.empty()){
			tx=state.front().first.first.first;
			ty=state.front().first.first.second;
			kx=state.front().first.second.first;
			ky=state.front().first.second.second;
			
			int time=state.front().second;
			state.pop();
			
			if(tx==kx && ty==ky){
				na=false;
				cout<<time<<endl;
				break;
			}
			
			rep(i,4){
				int ttx=tx+dx[i],tty=ty+dy[i],
					tkx=kx-dx[i],tky=ky-dy[i];
				
				if(ttx<0 || ttx>=x || tty<0 || tty>=y || d[ttx][tty]==1){
					ttx-=dx[i];
					tty-=dy[i];
				}
				if(tkx<0 || tkx>=x || tky<0 || tky>=y || d[tkx][tky]==1){
					tkx+=dx[i];
					tky+=dy[i];
				}
				pair<pair<int,int>,pair<int,int> > next=make_pair(make_pair(ttx,tty),make_pair(tkx,tky));
				
				if(past[ttx][tty][tkx][tky] || time>=99)continue;
				past[ttx][tty][tkx][tky]=1;
				state.push(make_pair(next,time+1));
			}
		}
		
		if(na)puts("NA");
	}
}