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<cstring>

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 ] == 1 )
			{
				tx = st.tx ;
				ty = st.ty ;
			}
			if( kx < 0 || kx >= w || ky < 0 || ky >= h || map[ ky ][ kx ] == 1 )
			{
				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<stdio.h>
#include<algorithm>
#include<queue>
using namespace std;
int m[50][50];
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
int bfs[50][50][50][50];
struct wolf{
	int a,b,c,d;
	wolf(int A,int B,int C,int D){
		a=A;
		b=B;
		c=C;
		d=D;
	}
};
int main(){
	int a,b;
	while(scanf("%d%d",&a,&b),a+b){
		int r1,r2,c1,c2;
		scanf("%d%d%d%d",&r1,&c1,&r2,&c2);
		for(int i=0;i<b;i++)
			for(int j=0;j<a;j++)
				scanf("%d",&m[i][j]);
		int inf=999999999;
		for(int i=0;i<b;i++)
			for(int j=0;j<a;j++)
				for(int k=0;k<b;k++)
					for(int l=0;l<a;l++)
						bfs[i][j][k][l]=inf;
		r1--;c1--;r2--;c2--;
		bfs[r1][c1][r2][c2]=0;
		queue<wolf> Q;
		Q.push(wolf(r1,c1,r2,c2));
		while(Q.size()){
			wolf at=Q.front();
			Q.pop();
			if(bfs[at.a][at.b][at.c][at.d]==99)continue;
			for(int i=0;i<4;i++){
				int s1=at.a+dx[i];
				int t1=at.b+dy[i];
				int s2=at.c-dx[i];
				int t2=at.d-dy[i];
				if(s1<0||s1>=b||m[s1][t1])s1-=dx[i];
				if(t1<0||t1>=a||m[s1][t1])t1-=dy[i];
				if(s2<0||s2>=b||m[s2][t2])s2+=dx[i];
				if(t2<0||t2>=a||m[s2][t2])t2+=dy[i];
				if(bfs[s1][t1][s2][t2]==inf){
					bfs[s1][t1][s2][t2]=bfs[at.a][at.b][at.c][at.d]+1;
					Q.push(wolf(s1,t1,s2,t2));
				}
			}
		}
		int ret=inf;
		for(int i=0;i<b;i++)for(int j=0;j<a;j++)ret=min(ret,bfs[i][j][i][j]);if(ret==inf)printf("NA\n");else printf("%d\n",ret);
	}
}

C++: #include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
#include<numeric>
using namespace std;
const int dx[]={1,0,-1,0};
const int dy[]={0,1,0,-1};
#define INF 1e+8
#define EPS 1e-7
#define PB push_back
#define fi first
#define se second
#define ll long long
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
class data{
    public:
    int ay;
    int ax;
    int by;
    int bx;
    int cnt;
    data(){}
    data(int _ay,int _ax,int _by,int _bx,int _cnt){
        ay = _ay;
        ax = _ax;
        by = _by;
        bx = _bx;
        cnt = _cnt;
    }
};
bool memo[52][52][52][52];
int main(){
    int W,H;
    while(scanf("%d%d",&W,&H),W){
        memset(memo,0,sizeof(memo));
        int ax,ay;
        int bx,by;
        int stage[52][52];
        scanf("%d%d",&ax,&ay);
        scanf("%d%d",&bx,&by);
        ax--;ay--;bx--;by--;
        rep(i,H){
            rep(j,W){
                scanf("%d",&stage[i][j]);
            }
        }
        queue < data > Q;
        Q.push(data(ay,ax,by,bx,0));
        memo[ay][ax][by][bx] = 1;
        int ans = -1;
        while(!Q.empty()){
            data d = Q.front();Q.pop();
            if(d.cnt > 99){
                break;
            }
            if(d.ax == d.bx && d.ay == d.by){
                ans = d.cnt;
                break;
            }
            rep(i,4){
                int nay,nax;
                int nby,nbx;
                nax = d.ax+dx[i];
                nay = d.ay+dy[i];
                nbx = d.bx+dx[(i+2)%4];
                nby = d.by+dy[(i+2)%4];
                if(nax < 0 || nax > W-1 || nay < 0 || nay > H-1)continue;
                if(nbx < 0 || nbx > W-1 || nby < 0 || nby > H-1)continue;
                if(stage[nay][nax] || stage[nby][nbx])continue;
                if(memo[nay][nax][nby][nbx])continue;
                memo[nay][nax][nby][nbx]  = 1;
                Q.push(data(nay,nax,nby,nbx,d.cnt+1));
                //printf("%d %d %d %d\n",nax,nay,nbx,nby);
            }
        }
        if(ans == -1)puts("NA");
        else printf("%d\n",ans);
    }
    return 0;
}