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 _, 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 += 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<iostream>
#include<cstring>
#include<algorithm>
#include<queue>

using namespace std;

const int MAX = 50;
const int INF = (1<<25);

bool 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};
struct data{
  int t,tx,ty,kx,ky;
  data(int t,int tx, int ty, int kx, int ky):t(t),tx(tx),ty(ty),kx(kx),ky(ky){}
};
queue<data> Q;

void init(){
  //fill(come[0][0][0],come[0][0][0]+MAX*MAX*MAX*MAX,INF);
  while(!Q.empty())Q.pop();
  memset(come,false,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;}

int bfs(){
  
  Q.push(data(0,stx-1,sty-1,skx-1,sky-1));

  while(!Q.empty()){
    data now = Q.front();
    Q.pop();

    if(now.t > 100) return -1;
    if(now.tx == now.kx && now.ty == now.ky) return now.t;
    
    if(come[now.tx][now.ty][now.kx][now.ky]) continue;
    come[now.tx][now.ty][now.kx][now.ky] = true;

     for(int i = 0; i < 4; i++){
      data nex = now;
      nex.tx += dx[i];
      nex.ty += dy[i];
      nex.kx -= dx[i];
      nex.ky -= dy[i];
      nex.t++;

      if(!isMovable(nex.tx,nex.ty)){
	nex.tx = now.tx;
	nex.ty = now.ty;
      }
      if(!isMovable(nex.kx,nex.ky)){
	nex.kx = now.kx;
	nex.ky = now.ky;
      }
      Q.push(nex);
    }
  }
  return -1;
}

void solve(){
  // dfs(0,stx-1,sty-1,skx-1,sky-1);
  int ans = bfs();
  if(ans == -1) cout << "NA" << endl;
  else cout << ans << endl;
}

int main(){
  while(cin >> w >> h && w+h){
    init();
    input();
    solve();
  }
  return 0;
}

C++: #include <cstdio>
#include <queue>
#include <map>
#include <algorithm>
#define Z(n)get<n>(z)
#define M make_pair
#define F first
#define S second
using namespace std;
typedef pair<int,int> pii;
typedef tuple<pii,pii,int> T;
int t[51][51],dx[]={-1,0,1,0},dy[]={0,-1,0,1},a,b,x,y,X,Y,i,j,k;
int main(){
	for(;scanf("%d%d",&a,&b),a;){
		map<pair<pii,pii>,int>m;
		scanf("%d%d%d%d",&x,&y,&X,&Y);x--,y--,X--,Y--;
		for(j=0;j<b;j++)for(i=0;i<a;i++)scanf("%d",t[i]+j);
		queue<T>q;
		m[M(M(x,y),M(X,Y))]=1;
		for(q.push(make_tuple(M(x,y),M(X,Y),0));!q.empty();){
			T z=q.front();q.pop();
			if(Z(0)==Z(1)){printf("%d\n",get<2>(z));goto OK;}
			if(Z(2)<100)for(i=0;i<4;i++){k=0;
				pii c1=make_pair(Z(0).F+dx[i],Z(0).S+dy[i]);
				if(!(0<=c1.F&&c1.F<a&&0<=c1.S&&c1.S<b&&!t[c1.F][c1.S]))c1=Z(0),k|=1;
				pii c2=make_pair(Z(1).F+dx[(i+2)%4],Z(1).S+dy[(i+2)%4]);
				if(!(0<=c2.F&&c2.F<a&&0<=c2.S&&c2.S<b&&!t[c2.F][c2.S]))c2=Z(1),k|=2;
				if(k<3&&!m[M(c1,c2)]){
					q.push(make_tuple(c1,c2,Z(2)+1));
					m[M(c1,c2)]=1;
				}
			}
		}
		puts("NA");
		OK:;
	}
}

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

class State{
public:
  int x1, y1, x2, y2, cost;

  State(){}
  State(int x1, int y1, int x2, int y2, int cost) :
    x1(x1), y1(y1), x2(x2), y2(y2), cost(cost) {}

  bool goal(){
    return x1 == x2 && y1 == y2;
  }
};

int w, h;
int t[52][52];
int sx, sy, gx, gy;

bool closed[52][52][52][52];

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

void move(int &x, int &y, int d){
  int nx = x + dx[d];
  int ny = y + dy[d];

  if(nx < 0 || w <= nx || ny < 0 || h <= ny || t[ny][nx] == 1){
    return;
  }
  x = nx;
  y = ny;
}

void solve(){
  queue<State> open;
  open.push(State(sx, sy, gx, gy, 0));
  memset(closed, 0, sizeof(closed));
  closed[sy][sx][gy][gx] = true;

  while(!open.empty()){
    State st = open.front();
    open.pop();

    if(st.cost >= 100){
      continue;
    }
    if(st.goal()){
      cout << st.cost << endl;
      return;
    }

    for(int i = 0; i < 4; i++){
      int nx1 = st.x1;
      int ny1 = st.y1;
      int nx2 = st.x2;
      int ny2 = st.y2;

      move(nx1, ny1, i);
      move(nx2, ny2, (i + 2) % 4);

      if(nx1 == st.x1 && ny1 == st.y1 &&
         nx2 == st.x2 && ny2 == st.y2) continue;
      if(closed[ny1][nx1][ny2][nx2]) continue;

      closed[ny1][nx1][ny2][nx2] = true;
      open.push(State(nx1, ny1, nx2, ny2, st.cost + 1));
    }
  }

  cout << "NA" << endl;
}

int main(){
  while(cin >> w >> h, w || h){
    cin >> sx >> sy;
    cin >> gx >> gy;
    sx--;
    sy--;
    gx--;
    gy--;

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

    solve();
  }
}