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<map>
using namespace std;
#define rep(i, n) for ( int i = 0; i < n; i++ )
#define MAX 50
#define INFTY (1<<10)

int H, W, G[MAX][MAX];

bool isBlock(int y, int x){
    if ( 0 > y || 0 > x || y >= H || x >= W ) return true;
    return G[y][x];
}

int bfs(int tx, int ty, int kx, int ky){
    queue<pair<int, int> > Q;
    map<pair<int, int>, int> D;
    int pt = ty*W + tx;
    int pk = ky*W + kx;
    D[make_pair(pt,pk)] = 0;
    Q.push(make_pair(pt, pk));

    pair<int, int> u, v;
    const int dy[4] = {0, -1, 0, 1};
    const int dx[4] = {1, 0, -1, 0};
    int nty, ntx, nky, nkx, npt, npk;

    while(!Q.empty()){
	u = Q.front(); Q.pop();
	ty = u.first/W;
	tx = u.first%W;
	ky = u.second/W;
	kx = u.second%W;
	pt = ty*W + tx;
	pk = ky*W + kx;
	if ( pt == pk ) return D[make_pair(pt,pk)];
	rep(r, 4){
	    nty = ty + dy[r];
	    ntx = tx + dx[r];
	    nky = ky + dy[r]*(-1);
	    nkx = kx + dx[r]*(-1);
	    npt = (isBlock(nty, ntx))? pt : nty*W+ntx;
	    npk = (isBlock(nky, nkx))? pk : nky*W+nkx;
	    if ( D.find(make_pair(npt, npk)) == D.end() ){
		D[make_pair(npt,npk)] = D[make_pair(pt,pk)] + 1;
		Q.push(make_pair(npt, npk));
	    }
	}
    }
    return -1;
}

main(){
    int tx, ty, kx, ky;
    while(1){
	cin >> W >> H;
	if ( W == 0 && H == 0 ) break;
	cin >> tx >> ty >> kx >> ky;
	tx--; ty--; kx--; ky--;
	rep(i, H) rep(j, W) G[i][j] = 1;
	rep(i, H) rep(j, W) cin >> G[i][j];
	int cost = bfs(tx, ty, kx, ky);
	if ( cost < 0 ) cout << "NA" << endl;
	else cout << cost << endl;
    }
}

C++: #include<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct Y{
int hx,hy,rx,ry,t;
};
int c[51][51][51][51],mp[52][52];
int main(){
int w,h,i,j,a[2]={1,-1},b[2];
Y e;
while(1){
queue<Y> q;
	cin>>w>>h;
	if(w==0&&h==0)break;
	cin>>e.hx>>e.hy>>e.rx>>e.ry;
	e.t=0;
	q.push(e);
	memset(c,0,sizeof(c));
	memset(mp,1,sizeof(mp));
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
			cin>>mp[i][j];
		}
	}
	while(!q.empty()){
		e=q.front();
		q.pop();
		c[e.hy][e.hx][e.ry][e.rx]=1;
		if(e.t>=100||e.hx==e.rx&&e.hy==e.ry)break;
		e.t++;
		for(i=0;i<2;i++){
			if(mp[e.hy+a[i]][e.hx]==0&&c[e.hy+a[i]][e.hx][e.ry-a[i]][e.rx]==0&&mp[e.ry-a[i]][e.rx]==0||mp[e.ry-a[i]][e.rx]==0&&c[e.hy][e.hx][e.ry-a[i]][e.rx]==0&&mp[e.hy+a[i]][e.hx]!=0||mp[e.hy+a[i]][e.hx]==0&&mp[e.ry-a[i]][e.rx]!=0&&c[e.hy+a[i]][e.hx][e.ry][e.rx]==0){
				b[0]=0;																										
				b[1]=0;																																		
				if(mp[e.hy+a[i]][e.hx]==0){																											
					e.hy+=a[i];																																			
					b[0]=1;																																					
				}																																													
				if(mp[e.ry-a[i]][e.rx]==0){																																										
					e.ry-=a[i];																																		
					b[1]=1;																																																														
				}		
				c[e.hy][e.hx][e.ry][e.rx]=1;																																																																																																																
				q.push(e);																											
				if(b[0]==1)e.hy-=a[i];																														
				if(b[1]==1)e.ry+=a[i];																											
			}																																																												
			if(mp[e.hy][e.hx+a[i]]==0&&mp[e.ry][e.rx-a[i]]==0&&c[e.hy][e.hx+a[i]][e.ry][e.rx-a[i]]==0||mp[e.hy][e.hx+a[i]]==0&&c[e.hy][e.hx+a[i]][e.ry][e.rx]==0&&mp[e.ry][e.rx-a[i]]!=0||mp[e.ry][e.rx-a[i]]==0&&mp[e.hy][e.hx+a[i]]!=0&&c[e.hy][e.hx][e.ry][e.rx-a[i]]==0){
				b[0]=0;
				b[1]=0;
				if(mp[e.hy][e.hx+a[i]]==0){
					e.hx+=a[i];
					b[0]=1;
				}
				if(mp[e.ry][e.rx-a[i]]==0){
					e.rx-=a[i];
					b[1]=1;
				}
				c[e.hy][e.hx][e.ry][e.rx]=1;
				q.push(e);
				if(b[0]==1)e.hx-=a[i];
				if(b[1]==1)e.rx+=a[i];
			}
		}
		e.t--;
	}
	if(e.hy==e.ry&&e.hx==e.rx)cout<<e.t<<endl;
	else cout<<"NA"<<endl;
}
return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <queue>
using namespace std;

struct S {
	int tx,ty;
	int kx,ky;
	int turn;
	S(int tx,int ty,int kx,int ky,int turn);
};

S::S(int _tx,int _ty,int _kx,int _ky,int _turn) {
	tx=_tx;
	ty=_ty;
	kx=_kx;
	ky=_ky;
	turn=_turn;
}

bool d[50][50];
bool vst[50][50][50][50];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	while(scanf("%d %d",&X,&Y),X||Y) {
		scanf("%d %d",&tx,&ty);
		scanf("%d %d",&kx,&ky);
		for(int j=0;j<Y;j++) {
			for(int i=0;i<X;i++) {
				scanf("%d",&d[i][j]);
			}
		}
		tx--;ty--;kx--;ky--;
		queue<S> q;
		bool ok=false;
		q.push(S(tx,ty,kx,ky,0));
		memset(vst,false,sizeof(vst));
		vst[tx][ty][kx][ky]=true;
		while(!q.empty()) {
			S s=q.front();q.pop();
			if(s.turn>=100) break;
			if(s.tx==s.kx&&s.ty==s.ky) {
				printf("%d\n",s.turn);
				ok=true;
				break;
			}
			for(int i=0;i<4;i++) {
				int ntx=s.tx+dx[i],nty=s.ty+dy[i];
				int nkx=s.kx-dx[i],nky=s.ky-dy[i];
				if(0>ntx||ntx>=X||0>nty||nty>=Y||d[ntx][nty]) {
					ntx-=dx[i],nty-=dy[i];
				}
				if(0>nkx||nkx>=X||0>nky||nky>=Y||d[nkx][nky]) {
					nkx+=dx[i],nky+=dy[i];
				}
				if(!vst[ntx][nty][nkx][nky]) {
					vst[ntx][nty][nkx][nky]=true;
					q.push(S(ntx,nty,nkx,nky,s.turn+1));
				}
			}
		}
		if(!ok) printf("NA\n");
	}
	return 0;
}