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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

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)
	//heap.Init(&pq)
	//heap.Push(&pq, start)
	//pq.Push(start)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*Status)
		now := pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			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 += 1
			if next.Turn < 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				pq = append(pq, next)
			}
		}
	}
	if ans == 101 {
		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<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct oza{
	int x;
	int y;
};
int A[52][52][52][52];
int main(){
	oza k;
	oza t;
	queue<oza> ka;
	queue<oza> ta;
	queue<int> Z;
	int  w,h,b;
	int d=0,c=0,i=0,j=0,l=-1,D[52][52];
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&w,&h);
	while(w!=0&&h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1; //??¨????????????????????\?????? 
		}
	}

	scanf("%d %d",&t.x,&t.y);
	scanf("%d %d",&k.x,&k.y);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	ta.push(t);
	ka.push(k);
	Z.push(c);
		if(t.x==k.x&&t.y==k.y){
			d=-1;
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		t=ta.front();
		k=ka.front();
		ka.pop();
		ta.pop();
		Z.pop();
		A[t.x][t.y][k.x][k.y]=1;
		}
		if(c==100||Z.empty()){
			printf("NA");
		break;
		}
	
		// ?????\????????????????????¨?????¨??????
		t=ta.front();
		k=ka.front();
		c=Z.front();
		
		t.x=t.x+tx[l];
		t.y=t.y+ty[l];
		k.x=k.x+kx[l];
		k.y=k.y+ky[l];
		
		if(D[t.x][t.y]==1){
		t.x=t.x-tx[l];
		t.y=t.y-ty[l];
		}
		if(D[k.x][k.y]==1){
		k.x=k.x-kx[l];
		k.y=k.y-ky[l];
		}
		if(A[t.x][t.y][k.x][k.y]==1){
			continue;
		}
		
		ta.push(t);
		ka.push(k);
		c=c+1;
		Z.push(c);
		
		if(t.x==k.x&&t.y==k.y){
			printf("%d\n",Z.back());
			break;
		}	
		
		
	}
	while(!ka.empty()){
	ka.pop();
	ta.pop();
	Z.pop();
	}
	c=0;
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>

using namespace std;
typedef long long LL;
static const double EPS = 1e-8;
static const int INF = (int)1e8;

#define FOR(i,k,n) for (int i=(k); i<(int)(n); ++i)
#define REP(i,n) for (int i=0; i<(int)(n); ++i)
#define FOREQ(i,k,n) for (int i=(k); i<=(int)(n); ++i)
#define FORIT(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define FIND(m,w) ((m).find(w)!=(m).end())
struct P{
  int tx,ty,kx,ky;
  int t;
  P(int tx,int ty,int kx,int ky,int t) : tx(tx),ty(ty),kx(kx),ky(ky),t(t) {}
};
bool operator < (P p, P q){
  return p.t > q.t;
}
int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};
bool memo[51][51][51][51];
int main(void){
  int w,h;
  while(cin>>w>>h,w){
    memset(memo,0,sizeof(memo));
    int grid[51][51];
    int tx,ty,kx,ky;
    cin>>tx>>ty>>kx>>ky;
    tx--;ty--;kx--;ky--;
    REP(y,h)REP(x,w)cin>>grid[y][x];
    priority_queue<P> que;
    que.push(P(tx,ty,kx,ky,0));
    int ans=-1;
    while(!que.empty()){
      P p = que.top(); que.pop();
      if(memo[p.tx][p.ty][p.kx][p.ky])continue;
      memo[p.tx][p.ty][p.kx][p.ky] = true;
      if(p.t>=100){
        ans = -1;
        break;
      }
      if(p.tx==p.kx&&p.ty==p.ky){
        ans = p.t;
        break;
      }
      REP(r,4){
        int ntx = p.tx + dx[r];
        int nty = p.ty + dy[r];
        int nkx = p.kx - dx[r];
        int nky = p.ky - dy[r];
        if(!(ntx>=0&&ntx<w&&nty>=0&&nty<h&&grid[nty][ntx]==0)){
          ntx = p.tx;
          nty = p.ty;
        }
        if(!(nkx>=0&&nkx<w&&nky>=0&&nky<h&&grid[nky][nkx]==0)){
          nkx = p.kx;
          nky = p.ky;
        }
        que.push(P(ntx,nty,nkx,nky,p.t+1));
      }
    }
    if(ans==-1) cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}