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<cstring>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
using namespace std;
struct P{
  P(){};
  P(int a,int b){
    x=a,y=b;
  }
  int x,y;
  void move(int,int);
};
struct S{
  S(){};
  S(P a,P b){
    t=a;
    k=b;
  }
  P t,k;
  void move(int);
};

P size;
S f_pos;
vector<vector<int> > f;
bool input(){
  size=P();
  f_pos=S();
  f.clear();
  cin>>size.y>>size.x;
  if(size.x==0&&size.y==0)return false;
  cin>>f_pos.t.y>>f_pos.t.x;
  cin>>f_pos.k.y>>f_pos.k.x;
  vector<int> t;
  for(int i=0;i<size.y+2;i++){
    t.push_back(1);
  }
  f.push_back(t);
  for(int i=0;i<size.x;i++){
    vector<int> tt;
    tt.push_back(1);
    for(int j=0;j<size.y;j++){
      int tmp;
      cin>>tmp;
      tt.push_back(tmp);
    }
    tt.push_back(1);
    f.push_back(tt);
  }
  f.push_back(t);
  return true;
}
int cost[60][60][60][60];
int getCost(S s){
  return cost[s.t.x][s.t.y][s.k.x][s.k.y];
}
const int vx[]={0,0,1,-1};
const int vy[]={1,-1,0,0};
void S::move(int i){
  t.move(vx[i],vy[i]);
  k.move(-vx[i],-vy[i]);
}
void P::move(int a,int b){
  if(f[x+a][y+b]!=1){
    x+=a;
    y+=b;
  }
}
int solve(){
  memset(cost,-1,(60*60*60*60));
  queue<S> q;
  q.push(f_pos);
  cost[f_pos.t.x][f_pos.t.y][f_pos.k.x][f_pos.k.y]=0;
  while(!q.empty()){
    S now = q.front();q.pop();
    for(int i=0;i<4;i++){
      S tmp = now;
      tmp.move(i);
      if(cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y]!=-1)continue;

      cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y] = getCost(now)+1;
      if(getCost(tmp)>=100){
        return -1;
      }else if( (tmp.t.x==tmp.k.x)&&(tmp.t.y==tmp.k.y) ){
        return cost[tmp.t.x][tmp.t.y][tmp.k.x][tmp.k.y];
      }else{
        q.push(tmp);
      }
    }
  }
  return -1;
}
int main(){
  while(input()){
    int ans= solve();
    if(ans==-1||ans>=100){
      cout<<"NA"<<endl;
    }else{
      cout<<ans<<endl;
    }
  }
}

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

bool went[50 + 10][50 + 10][50 + 10][50 + 10] = { 0 };

int map[50 + 10][50 + 10]/* = { 0 }*/;

int gx[] = { 1,0,-1,0,-1,0,1,0 };
int gy[] = { 0,1,0,-1,0,-1,0,1 };

struct ST
{
	int tx, ty;
	int kx, ky;
	int tim=0;
};

bool ChekNow(ST);


ST GoMap(ST, int);

void test(ST ex, int h, int w)
{
	int i, j;
	cout << endl;
	for (i = 1; i <= h; i++)
	{
		for (j = 1; j <= w; j++)
		{
			if ((i == ex.ky && j == ex.kx) || (i == ex.ty && j == ex.tx))
				cout << "*";
			else cout << map[i][j];
		}
		cout << endl;
	}
	cout << ex.tim << endl;
}


int main()
{
	ST now,tmp;

	queue <ST> nx;


	int w, h;
	int tsx, tsy;
	int ksx, ksy;

	bool flg;
	int i, j;

	while (cin >> w >> h, w != 0 && h != 0)
	{
		flg = true;

		cin >> tsx >> tsy;
		cin >> ksx >> ksy;
		
		for (i = 1; i <= h; i++)
		{
			map[i][0] = map[i][w + 1] = 1;

			for (j = 1; j <= w; j++)
			{
				cin >> map[i][j];
			}
		}

		for (i = 0; i <= w + 1; i++)
		{
			map[0][i] = 1;
			map[h + 1][i] = 1;
		}


		now.tx = tsx;
		now.ty = tsy;
		now.kx = ksx;
		now.ky = ksy;
		now.tim = 0;

		nx.push(now);

		while (!nx.empty()) // && now.tim<100)
		{
			now = nx.front();
			nx.pop();


			if (now.tim >= 100)
			{
				break;
			}


			//if (ChekNow(now))
			//{
			//	continue;
			//}
			//went[now.tx][now.ty][now.kx][now.ky] = true;


			//test(now, h, w);


			if (now.tx == now.kx && now.ty == now.ky)
			{
				cout << now.tim << endl;

				flg = false;

				break;
			}

			for (i = 0; i < 4; i++)
			{
				//tmp=GoMap(now, i);


				tmp = now;

				if (map[now.ty + gy[i]][now.tx + gx[i]] == 0)
				{
					tmp.ty += gy[i];
					tmp.tx += gx[i];
				}
				if (map[now.ky + gy[i + 4]][now.kx + gx[i + 4]] == 0)
				{
					tmp.ky += gy[i + 4];
					tmp.kx += gx[i + 4];
				}


				if (!ChekNow(tmp))
				{
					tmp.tim++;

					went[tmp.tx][tmp.ty][tmp.kx][tmp.ky] = true;

					nx.push(tmp);
				}
			}
		}

		if (flg)
		{
			cout << "NA\n";
		}

		while (!nx.empty())
		{
			nx.pop();
		}


		memset(went, 0, sizeof(went));
	}
	return 0;
}


bool ChekNow (ST ex)
{
	return went[ex.tx][ex.ty][ex.kx][ex.ky];
}


ST GoMap(ST ex, int i)
{
	if (map[ex.ty + gy[i]][ex.tx + gx[i]] == 0)
	{
		ex.ty += gy[i];
		ex.tx += gx[i];
	}
	if (map[ex.ky + gy[i + 4]][ex.kx + gx[i + 4]] == 0)
	{
		ex.ky += gy[i + 4];
		ex.kx += gx[i + 4];
	}


	return ex;
}