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 now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			continue
		}
		if ans<=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<bits/stdc++.h>
#define inf 1<<29
using namespace std;

class State{
public:
  int a,b,c,d;
  State(int a,int b,int c,int d):a(a),b(b),c(c),d(d){};
};

int h,w;
int table[51][51],memo[51][51][51][51];
int Y[4]={-1,0,1,0};
int X[4]={0,1,0,-1};

bool in(int a,int b){
  if(a<0 || b<0 || h<=a || w<=b)return false;
  return true;
}

void init(){
  for(int i=0;i<51;i++)
    for(int j=0;j<51;j++)
      for(int k=0;k<51;k++)
	for(int l=0;l<51;l++)memo[i][j][k][l]=inf;
}

int main()
{
  int a,b,c,d;
  while(1){
    cin>>w>>h;
    if(h+w==0)break;
    cin>>b>>a>>d>>c;
    a--;b--;c--;d--;
    for(int i=0;i<h;i++)for(int j=0;j<w;j++)cin>>table[i][j];
    init();

    queue<State> q;
    q.push(State(a,b,c,d));
    memo[a][b][c][d]=0;

    int ans=inf;
    while(!q.empty()){
      State u=q.front();
      q.pop();
      if(u.a==u.c && u.b==u.d){
	ans=min(memo[u.a][u.b][u.c][u.d],ans);
	continue;
      }
      for(int i=0;i<4;i++){
	int A=u.a+Y[i],B=u.b+X[i],C=u.c+Y[(i+2)%4],D=u.d+X[(i+2)%4];
	if(!in(A,B))continue;
	if(!in(C,D))continue;
	if(table[A][B]){
	  A=u.a;
	  B=u.b;
	}
	if(table[C][D]){
	  C=u.c;
	  D=u.d;
	}
	if(memo[A][B][C][D]==inf){
	  q.push(State(A,B,C,D));
	  memo[A][B][C][D]=memo[u.a][u.b][u.c][u.d]+1;
	}
      }
    }
    if(ans==inf || ans>=100)cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
 
using namespace std;
 
struct State{
    int tx, ty, kx, ky;
    State(int tx, int ty, int kx, int ky) : tx(tx), ty(ty), kx(kx), ky(ky) {} 
};
 
#define MAX 51
#define INF 1e9
 
int H, W, tx, ty, kx, ky;
int field[MAX][MAX];
const int ttx[] = {-1, 0, 0, 1};
const int tty[] = {0, -1, 1, 0};
const int kkx[] = {1, 0, 0, -1};
const int kky[] = {0, 1, -1, 0};
 
bool inField(int y, int x)
{
    return (0 <= y && y < H && 0 <= x && x < W);
}
 
int bfs()
{
    bool vis[MAX][MAX][MAX][MAX];
    memset(vis, false, sizeof(vis));
    vis[ty][tx][ky][kx] = true;
    queue<State> Q;
    Q.push(State(tx,ty,kx,ky));
    queue<int> cnt;
    cnt.push(0);
 
    int res = INF;
    while (!Q.empty()) {
	State s = Q.front(); Q.pop();
	int _cnt = cnt.front(); cnt.pop();
 
	if (_cnt == 100) break;
	if (s.tx == s.kx && s.ty == s.ky) {
	    res = min(res, _cnt);
	    break;
	}
 
	for (int i = 0; i < 4; i++) {
	    int ntx = s.tx + ttx[i], nty = s.ty + tty[i];
	    int nkx = s.kx + kkx[i], nky = s.ky + kky[i];
 
	    if (!inField(nty, ntx) || field[nty][ntx] == 1) {
		ntx = s.tx, nty = s.ty;
	    }
	    if (!inField(nky, nkx) || field[nky][nkx] == 1) {
		nkx = s.kx, nky = s.ky;
	    }
 
	    if (vis[nty][ntx][nky][nkx]) continue;
	    vis[nty][ntx][nky][nkx] = true;
	    Q.push(State(ntx, nty, nkx, nky));
	    cnt.push(_cnt+1);
	}
    }
    return res;
}
 
int main()
{
    while (cin >> W >> H, (W | H)) {
	cin >> tx >> ty >> kx >> ky;
	tx--, ty--, kx--, ky--;
	for (int i = 0; i < H; i++) {
	    for (int j = 0; j < W; j++) {
		cin >> field[i][j];
	    }
	}
	int res = bfs();
	if (res == INF) {
	    cout << "NA" << endl;
	} else {
	    cout << res << endl;
	}
    }
    return 0;
}

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;
}