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<cstring>
#include<algorithm>

using namespace std;

const int MAX = 50;
const int INF = (1<<25);

int come[MAX][MAX][MAX][MAX];
int M[MAX][MAX];
int w,h,stx,sty,skx,sky;
int dx[] = {1,-1,0,0};
int dy[] = {0,0,1,-1};
void init(){
  //fill(come[0][0][0],come[0][0][0]+MAX*MAX*MAX*MAX,INF);
  memset(come,-1,sizeof(come));
}

void input(){
  cin >> stx >> sty >> skx >> sky;
  for(int i = 0; i < h; i++)
    for(int j = 0; j < w; j++) cin >> M[i][j];
}

bool isMovable(int x, int y){return 0<=x&&x<w&&0<=y&&y<h&&M[y][x]==0;}
void dfs(int t, int tx, int ty, int kx, int ky){

  if(t > 100 || come[tx][ty][kx][ky] <= t && come[tx][ty][kx][ky] != -1) return;
  come[tx][ty][kx][ky] = t;

  for(int i = 0; i < 4; i++){
    int ntx = tx+dx[i];
    int nty = ty+dy[i];
    int nkx = kx-dx[i];
    int nky = ky-dy[i];

    int move = 0;
    if(!isMovable(ntx,nty)){
      ntx = tx;
      nty = ty;
      move++;
    }
    if(!isMovable(nkx,nky)){
      nkx = kx;
      nky = ky;
      move++;
    }
    if(move == 2) return;

    dfs(t+1,ntx,nty,nkx,nky);
  }
}

void solve(){
  dfs(0,stx-1,sty-1,skx-1,sky-1);
  
  int ans = INF;
  for(int i = 0; i < w; i++)
    for(int j = 0; j < h; j++)
      if(come[i][j][i][j] != -1) ans = min(ans,come[i][j][i][j]);

  if(ans == INF) cout << "NA" << endl;
  else cout << ans << endl;
}

int main(){
  while(cin >> w >> h && w+h){
    init();
    input();
    solve();
  }
  return 0;
}

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

const int INF=100000000;

class Point{
public:
  int tx;
  int ty;
  int kx;
  int ky;
};

int main(){
  while(true){
    int X,Y;
    cin>>X>>Y;
    if(X==0&&Y==0){
      break;
    }
    char F[X+1][Y+1];
    int D[X+1][Y+1];
    for(int x=1;x<=X;x++){
      for(int y=1;y<=Y;y++){
        D[x][y]=INF;
      }
    }
    int tx,ty;
    cin>>tx>>ty;
    int kx,ky;
    cin>>kx>>ky;
    D[tx][ty]=0;
    D[kx][ky]=0;

    for(int x=0;x<=X+2;x++){
      for(int y=0;y<=Y+2;y++){
        F[x][y]=1;
      }
    }
    int a;
    for(int x=1;x<=X;x++){
      for(int y=1;y<=Y;y++){
        cin>>a;
        F[x][y]=a;
      }
    }

    queue<Point> que;

    Point p;
    p.tx=tx;
    p.ty=ty;
    p.kx=kx;
    p.ky=ky;
    que.push(p);

    while(!que.empty()){
      p=que.front();
      que.pop();
      cout<<p.tx<<" "<<p.ty<<" "<<p.kx<<" "<<p.ky<<endl;

      if(p.tx==p.kx&&p.ty==p.ky){
        if(D[p.tx][p.ty]>100){
          cout<<"NA"<<endl;
        }
        cout<<D[p.tx][p.ty]<<endl;
        cout<<p.tx<<" "<<p.ty<<" "<<p.kx<<" "<<p.ky<<endl;
        break;
      }

      if(D[p.tx-1][p.ty]==INF&&D[p.kx+1][p.ky]==INF){
        Point q;
        q.tx=p.tx-1;
        q.ty=p.ty;
        q.kx=p.kx+1;
        q.ky=p.ky;
        if(F[q.tx][q.ty]==1){
          q.tx=q.tx+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.kx=q.kx-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }
        que.push(q);
      }

      if(D[p.tx+1][p.ty]==INF&&D[p.kx-1][p.ky]==INF){
        Point q;
        q.tx=p.tx+1;
        q.ty=p.ty;
        q.kx=p.kx-1;
        q.ky=p.ky;
        if(F[q.tx][q.ty]==1){
          q.tx=q.tx-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.kx=q.kx+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }
        que.push(q);
      }

      if(D[p.tx][p.ty+1]==INF&&D[p.kx][p.ky-1]==INF){
        Point q;
        q.tx=p.tx;
        q.ty=p.ty+1;
        q.kx=p.kx;
        q.ky=p.ky-1;
        que.push(q);
        if(F[q.tx][q.ty]==1){
          q.ty=q.ty-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.ky=q.ky+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }
        que.push(q);
      }

      if(D[p.tx][p.ty-1]==INF&&D[p.kx][p.ky+1]==INF){
        Point q;
        q.tx=p.tx;
        q.ty=p.ty-1;
        q.kx=p.kx;
        q.ky=p.ky+1;
        if(F[q.tx][q.ty]==1){
          q.ty=q.ty+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.ky=q.ky-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }
        que.push(q);
      }

    }
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct po{int x,y,a,b;};
int w,h;
int mp[55][55];
int tx,ty,kx,ky;
int dis[55][55][55][55];
 
po mkp(int a,int b,int c,int d){
  po res;
  res.x=a, res.y=b, res.a=c,res.b=d;
  return res;
}
 
int bfs(){
  int dx[]={0,0,-1,1};
  int dy[]={1,-1,0,0};
  memset(dis,0,sizeof(dis));
  queue <po> Q;
  Q.push(mkp(tx,ty,kx,ky));
 
  while(!Q.empty()){
    po t=Q.front();Q.pop();
 
    if(dis[t.y][t.x][t.b][t.a]>=100) return -1;
    if(t.x==t.a&&t.y==t.b) return dis[t.y][t.x][t.b][t.a];
     
 
    for(int i=0;i<4;i++){
      int nx=t.x+dx[i],ny=t.y+dy[i];
      int na=t.a-dx[i],nb=t.b-dy[i];
      if(nx<0||ny<0||nx>=w||ny>=h||mp[ny][nx])nx=t.x,ny=t.y;
      if(na<0||nb<0||na>=w||nb>=h||mp[nb][na])na=t.a,nb=t.b;
      if(nx==t.x&&ny==t.y&&na==t.a&&nb==t.b)continue;
      if(dis[ny][nx][nb][na])continue;
      dis[ny][nx][nb][na]=dis[t.y][t.x][t.b][t.a]+1;
      Q.push(mkp(nx,ny,na,nb));
    }
  }
  return -1;
}
 
int main(){
 
  while(1){
  cin>>w>>h;
  if(!w&&!h)break;
  cin>>tx>>ty>>kx>>ky;
  tx--,ty--,kx--,ky--;
  for(int i=0;i<h;i++)
    for(int j=0;j<w;j++) cin>>mp[i][j];
  int res=bfs();
  if(res==-1) cout << "NA"<<endl;
  else cout <<res<<endl;
  }
  return 0;
}