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)
	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)
		if ans <= now.Turn {
			continue
		}
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		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)
			}
		}
	}
	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<iostream>
#include<queue>
using namespace std;

bool isnot_table[51][51][51][51];

const int rightmove = 1;
const int leftmove = -1;
const int up = -1;
const int down = 1;

struct Point{
  int x;
  int y;
};

struct DoublePoint{
  Point m;
  Point l;
  int count;
};

int main(){

    while(1){

      int w,h;

      cin >> w >> h;

      if(w==0 && h==0)
        break;

      int table[w][h];

      DoublePoint bro;

      cin >> bro.m.x >> bro.m.y >> bro.l.x >> bro.l.y;

      bro.count = 0;

      for(int i=0;i<w;i++){
        for(int j=0;j<h;j++){
          cin >> table[i][j];
        }
      }

      if(bro.m.x == bro.l.x && bro.l.x == bro.l.y){
        cout << 0 << endl;
        continue;
      }


      for(int i=0;i<w;i++){
        for(int j=0;j<h;j++){
          if(table[i][j]==0){
            isnot_table[i][j][i][j] = true;
          }
          else{
            isnot_table[i][j][i][j] = false;
          }
        }
      }

      isnot_table[bro.m.x][bro.m.y][bro.l.x][bro.l.y] = false;

      queue<DoublePoint> q;

      q.push(bro);

      while(!q.empty()){

        DoublePoint BefroreTwin = q.front();

        q.pop();

        BefroreTwin.count++;

        DoublePoint tmp = BefroreTwin;


        if(table[tmp.m.x+leftmove][tmp.m.y]==0){
          tmp.m.x += leftmove;
        }
        if(table[tmp.l.x+rightmove][tmp.l.y]==0){
          tmp.l.x += rightmove;
        }

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
          if(tmp.m.x == tmp.l.x && tmp.l.x == tmp.l.y){
            cout << tmp.count << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }
        tmp = BefroreTwin;


        if(table[tmp.m.x+rightmove][tmp.m.y]==0){
          tmp.m.x += rightmove;
        }
        if(table[tmp.l.x+leftmove][tmp.l.y]==0){
          tmp.l.x += leftmove;
        }

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
          if(tmp.m.x == tmp.l.x && tmp.l.x == tmp.l.y){
            cout << tmp.count << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);

        }

        tmp = BefroreTwin;


        if(table[tmp.m.x][tmp.m.y+up]==0){
          tmp.m.x += up;
        }
        if(table[tmp.l.x][tmp.l.y+down]==0){
          tmp.l.x += down;
        }

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
          if(tmp.m.x == tmp.l.x && tmp.l.x == tmp.l.y){
            cout << tmp.count << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }

        tmp = BefroreTwin;


        if(table[tmp.m.x][tmp.m.y+down]==0){
          tmp.m.x += down;
        }
        if(table[tmp.l.x][tmp.l.y+up]==0){
          tmp.l.x += up;
        }

        if(isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y]){
          if(tmp.m.x == tmp.l.x && tmp.l.x == tmp.l.y){
            cout << tmp.count << endl;
            break;
          }
          isnot_table[tmp.m.x][tmp.m.y][tmp.l.x][tmp.l.y] = false;
          q.push(tmp);
        }

      }

    }
    return 0;
}

C++: #include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<algorithm>
#define limX(a)(min(max(1,a),X))
#define limY(a)(min(max(1,a),Y))
using namespace std;
typedef struct d{int tx,ty,kx,ky,time;}D;
int G[55][55],X,Y,R,tx,ty,kx,ky,mx[4]={0,-1,0,1},my[4]={-1,0,1,0},F[51][51][51][51];
struct Order{bool operator ()(D const& a, D const& b) const{return a.time>b.time;}};

int main()
{
	D tmp,tmp2;
	for(;scanf("%d%d",&X,&Y),X;)
	{
		memset(F,0,sizeof(F));
		priority_queue<D,vector<D>,Order>Q;
		R=-1;
		tmp.time=0;
		scanf("%d%d%d%d",&tmp.tx,&tmp.ty,&tmp.kx,&tmp.ky);
		for(int i=1;i<=Y;i++)for(int j=1;j<=X;j++)scanf("%d",&G[i][j]);
		Q.push(tmp);
		for(;!Q.empty();)
		{
			tmp=tmp2=Q.top();Q.pop();
			if(tmp.time>100)break;
			if(tmp.kx==tmp.tx&&tmp.ky==tmp.ty){R=tmp.time;break;}
			for(int i=0;i<4;tmp=tmp2,i++)
			{
				tmp.kx=limX(tmp.kx+mx[i]);
				tmp.ky=limY(tmp.ky+my[i]);
				if(G[tmp.ky][tmp.ky])tmp.kx=tmp2.kx,tmp.ky=tmp2.ky;
				tmp.tx=limX(tmp.tx-mx[i]);
				tmp.ty=limY(tmp.ty-my[i]);
				if(G[tmp.ty][tmp.ty])tmp.tx=tmp2.tx,tmp.ty=tmp2.ty;
				tmp.time++;
				if(!F[tmp.kx][tmp.ky][tmp.tx][tmp.ty])
				{
					F[tmp.kx][tmp.ky][tmp.tx][tmp.ty]=1;
					Q.push(tmp);
				}
			}
		}
		if(R==-1)
			puts("NA");
		else
			printf("%d\n",R);
	}
}