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 <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(cin>>X>>Y,X||Y) {
		cin>>tx>>ty>>kx>>ky;
		for(int j=0;j<Y;j++) {
			for(int i=0;i<X;i++) {
				cin>>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) {
				cout<<s.turn<<endl;
				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) cout<<"NA"<<endl;
	}
	return 0;
}

C++: #include<cstdio>
#include<queue>
#include<vector>
#include<set>
using namespace std;
struct xy{
    int x,y;
    xy(int a,int b){
        x=a;
        y=b;
    }
    bool operator<(const xy &other) const{
        if(x<other.x) return true;
        if(y<other.y) return true;
        return false;
    }
    bool operator==(const xy &other) const{
        if(x==other.x && y==other.y) return true;
        return false;
    }
};

int main(){
    int vtx[]={1,0,-1,0},vty[]={0,1,0,-1};
    int vkx[]={-1,0,1,0},vky[]={0,-1,0,1};
    for(;;){
        int X,Y,tx,ty,kx,ky;
        scanf("%d%d",&X,&Y);
        if(X==0 && Y==0) break;
        vector<vector<int> > mmap(X,vector<int>(Y));
        set<pair<xy,xy> > ms;
        scanf("%d%d%d%d",&tx,&ty,&kx,&ky);
        tx--;
        ty--;
        kx--;
        ky--;
        for(int i=0;i<Y;i++){
            for(int j=0;j<X;j++){
                scanf("%d",&mmap[j][i]);
            }
        }
        queue<pair<pair<xy,xy>,pair<xy,xy> > > goqt;
        for(int i=0;i<4;i++){
            goqt.push(make_pair(make_pair(xy(tx,ty),xy(tx+vtx[i],ty+vty[i])),make_pair(xy(kx,ky),xy(kx+vkx[i],kx+vky[i]))));
        }
        ms.insert(make_pair(xy(tx,ty),xy(kx,ky)));
        int ii;
        for(ii=1;ii<100;ii++){
            int TSIZE=goqt.size();
//            printf("%d\n",goqt.size());
            for(int i=0;i<TSIZE;i++){
                pair<pair<xy,xy>,pair<xy,xy> > tt=goqt.front();
                goqt.pop();
                xy tfrom=tt.first.first,tnow=tt.first.second,kfrom=tt.second.first,know=tt.second.second;
                if(tnow.x<0 || tnow.x>=X || tnow.y<0 || tnow.y>=Y || mmap[tnow.x][tnow.y]==1) tnow=tfrom;
                if(know.x<0 || know.x>=X || know.y<0 || know.y>=Y || mmap[know.x][know.y]==1) know=kfrom;
                if(tnow.x==know.x && tnow.y==know.y){
                    goto TO;
                }
                if(ms.find(make_pair(tnow,know))==ms.end()){
                    for(int iv=0;iv<4;iv++){
                        printf("(%d,%d)(%d,%d)\n",tnow.x,tnow.y,know.x,know.y);
                        goqt.push(make_pair(make_pair(tnow,xy(tnow.x+vtx[iv],tnow.y+vty[iv])),make_pair(know,xy(know.x+vkx[iv],know.y+vky[iv]))));
                    }
                    ms.insert(make_pair(tnow,know));
                }
            }
            printf("%d\n",ii);
        }
TO:
        if(ii==100) printf("NA\n");
        else printf("%d\n",ii);
    }
}

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

using namespace std;

#define MAX 51

int xy[MAX][MAX];
int cost[MAX][MAX][MAX][MAX];
int X,Y;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int co;
  state(){}
  state(int tx,int ty,int kx,int ky,int co):
    tx(tx),ty(ty),kx(kx),ky(ky),co(co){}
};

int solve(int tx,int ty,int kx,int ky){

  memset(cost,101,sizeof(cost));

  queue<state> q;
  q.push( state(tx,ty,kx,ky,0) );

  while( !q.empty() ){
    state p=q.front();
    q.pop();

    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;

    cost[tx][ty][kx][ky]=p.co;

    for(int i=0;i<4;i++){

      int f=0;
      
      if(p.co+1>=100) continue;
      
      if(kx+dx[i]*-1 <= 0 || ky+dy[i]*-1 <=0 || kx+dx[i]*-1 > X || ky+dy[i]*-1 > Y)
	f+=10;      
      if(tx+dx[i] <= 0 || ty+dy[i] <= 0 || tx+dx[i] > X || ty+dy[i] > Y )
	f++;

      if( xy[ty+dy[i]][tx+dx[i]]==1 )
	f++;
      if(xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	f+=10;

      if(f==0){
	if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1)
	  return p.co+1;
      }

      if(f/10>0 && f%10>0)
	continue;

      if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] < p.co)
	continue;

      if(f==0)
	q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );
      else if(f%10>0)
	q.push( state(tx,ty,kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );
      else if(f/10>0)
	q.push( state(tx+dx[i],ty+dy[i],kx,ky,p.co+1) );
    }
  }
  return -1;
} 

main(){
  
  int i,j;
  int kx,ky,tx,ty;
  int n;

  while(1){
    
    cin >> X >> Y;

    if(X==0 && Y==0) break;
    
    cin >> tx >> ty;
    cin >> kx >> ky;
    
    for(i=1;i<=Y;i++){
      for(j=1;j<=X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx,ty,kx,ky);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}