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 := 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 <cstdio>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <queue>
#include <algorithm>
using namespace std;
typedef pair<int,int> P1;
typedef pair<P1,P1> P2;
typedef pair<int,P2> P3;
int d[50][51];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
bool used[50][50][50][50];
int main() {
	int X,Y;
	while(scanf("%d %d",&X,&Y),X) {
		int tx,ty,kx,ky;
		scanf("%d %d",&tx,&ty); tx--;ty--;
		scanf("%d %d",&kx,&ky); kx--;ky--;
		for(int i=0;i<Y;i++) {
			for(int j=0;j<X;j++) scanf("%d",&d[i][j]);
		}
		queue<P3> Q;
		Q.push(P3(0,P2(P1(tx,ty),P1(kx,ky))));
		used[tx][ty][kx][ky]=1;
		int cur=0;
		bool NA=1;
		while(!Q.empty()) {
			P3 p3=Q.front();Q.pop();
			int tx=p3.second.first.first;
			int ty=p3.second.first.second;
			int kx=p3.second.second.first;
			int ky=p3.second.second.second;
			if(p3.first>=100) break;
			if(tx==kx&&ty==ky) {
				printf("%d\n",p3.first);
				NA=0;
				break;
			}
			for(int i=0;i<4;i++) {
				int ntx=tx+dx[i],nty=ty+dy[i];
				int nkx=kx-dx[i],nky=ky-dy[i];
				if(0>ntx||ntx>=X||0>nty||nty>=Y||d[nty][ntx]) {
					ntx=tx,nty=ty;
				}
				if(0>nkx||nkx>=X||0>nky||nky>=Y||d[nky][nkx]) {
					nkx=kx,nky=ky;
				}
				if(!used[ntx][nty][nkx][nky]) {
					used[ntx][nty][nkx][nky]=1;
					Q.push(P3(p3.first+1,P2(P1(ntx,nty),P1(nkx,nky))));
				}
			}
		}
		if(NA) printf("NA\n");
	}
}

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

typedef pair<int,int> PA;
typedef pair<PA,PA> PPA;

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

int masu[55][55][55][55];  

int main(){
  
  int w,h,tx,ty,kx,ky,ans;
  int d[55][55];

  while(cin >> w >> h,w!=0&&h!=0){
    cin >> tx >> ty >> kx >> ky;
    tx--;
    ty--;
    kx--;
    ky--;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	cin >> d[i][j];
      }
    }
    
    ans = 101;
    
    queue<PPA> que;
    
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	for(int k=0;k<h;k++){
	  for(int l=0;l<w;l++) masu[i][j][k][l] = -1;
	}
      }
    }
    masu[ty][tx][ky][kx] = 0;
    que.push(PPA(PA(ty,tx),PA(ky,kx)));
    
    while(!que.empty()){
      PPA p = que.front();
      que.pop();
      
      int y1 = p.first.first;
      int x1 = p.first.second;
      int y2 = p.second.first;
      int x2 = p.second.second;
      
      for(int i=0;i<4;i++){
	int ay = y1 + dy[i];
	int ax = x1 + dx[i];
	if(d[ay][ax] == 1){
	  ay = y1;
	  ax = x1;
	}
	int by = y2 - dy[i];
	int bx = x2 - dx[i];
	if(d[by][bx] == 1){
	  by = y2;
	  bx = x2;
	}
	if(ay<0||ay>=h||ax<0||ax>=w||by<0||by>=h||bx<0||bx>=w||masu[ay][ax][by][bx]!=-1) continue;
	masu[ay][ax][by][bx] = masu[y1][x1][y2][x2]+1;
	
	if(masu[ay][ax][by][bx] >= 100) continue;
	que.push(PPA(PA(ay,ax),PA(by,bx)));
	
	if(ay==by&&ax==bx) ans = min(ans,masu[ay][ax][by][bx]);
	
      }
    }
    
    if(ans >= 100) cout << "NA" << endl;
    else cout << ans << endl;
    
  }
  return(0);
}