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<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define INF 1<<10

int xs[] = {0, 1, 0, -1}, ys[] = {1, 0, -1, 0};
int x, y;
int field[50][50];
short int  dp[50][50][50][50];

short int solve(int tx, int ty, int kx, int ky, int depth){
  if(depth > INF)return INF;
  int ntx, nty, nkx, nky;
  if(dp[tx][ty][kx][ky] != -1){
    return dp[tx][ty][kx][ky];
  }
  dp[tx][ty][kx][ky] = INF;
  for(int i = 0;i < 4;i++){
    ntx = tx + xs[i];
    nty = ty + ys[i];
    nkx = kx - xs[i];
    nky = ky - ys[i];
    if(ntx < 0 || ntx >= x || nty < 0 || nty >= y || field[ntx][nty] == 1){
      ntx = tx;
      nty = ty;
    }
    if(nkx < 0 || nkx >= x || nky < 0 || nky >= y || field[nkx][nky] == 1){
      nkx = kx;
      nky = ky;
    }
    dp[tx][ty][kx][ky] = min(dp[tx][ty][kx][ky], (short int) (solve(ntx, nty, nkx, nky, depth + 1) + 1));
  }
  return dp[tx][ty][kx][ky];
}

int main(){
  int tx, ty, kx, ky;
  while(true){
    scanf("%d%d", &x, &y);
    memset(dp, -1, sizeof(dp));
    if(x == 0 && y == 0) return 0;
    scanf("%d%d", &tx, &ty);
    scanf("%d%d", &kx, &ky);
    for(int i = 0;i < y;i++){
      for(int j = 0;j < x;j++){
	scanf("%d", &field[j][i]);
	dp[i][j][i][j] = 0;
      }
    }
    short int ans = solve(tx - 1, ty - 1, kx - 1, ky - 1, 0);
    if(ans >= 100)
      puts("NA");
    else
      printf("%d\n", ans);
  }
}

C++: // 2011/07/16 Tazoe

#include <iostream>
#include <queue>
#include <map>
using namespace std;

struct state{
	int tx;
	int ty;
	int kx;
	int ky;
	int tim;
};

int main()
{
	while(true){
		int X, Y;
		cin >> X >> Y;
		if(X==0&&Y==0)
			break;

		int d[52][52];
		for(int y=0; y<=Y+1; y++)
			for(int x=0; x<=X+1; x++)
				d[y][x] = 1;

		struct state now;
		cin >> now.tx >> now.ty;
		cin >> now.kx >> now.ky;
		now.tim = 0;

		queue<struct state> que;
		que.push(now);

		map<int, bool> memo;


		for(int y=1; y<=Y; y++)
			for(int x=1; x<=X; x++)
				cin >> d[y][x];

		while(true){
			if(que.empty()){
				cout << "NA" << endl;
				break;
			}

			now = que.front();
			que.pop();

			if(memo.find(((now.tx*100+now.ty)*100+now.kx)*100+now.ky)!=memo.end())
				continue;
			else
				memo[((now.tx*100+now.ty)*100+now.kx)*100+now.ky] = true;

			if(now.tim>=100){
				cout << "NA" << endl;
				break;
			}

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

			struct state nxt = now;
			if(d[nxt.ty-1][nxt.tx]==0)
				nxt.ty--;
			if(d[nxt.ky+1][nxt.kx]==0)
				nxt.ky++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty+1][nxt.tx]==0)
				nxt.ty++;
			if(d[nxt.ky-1][nxt.kx]==0)
				nxt.ky--;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx-1]==0)
				nxt.tx--;
			if(d[nxt.ky][nxt.kx+1]==0)
				nxt.kx++;
			nxt.tim++;
			que.push(nxt);

			nxt = now;
			if(d[nxt.ty][nxt.tx+1]==0)
				nxt.tx++;
			if(d[nxt.ky][nxt.kx-1]==0)
				nxt.kx--;
			nxt.tim++;
			que.push(nxt);
		}
	}

	return 0;
}

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() && tmp.tim<100)
		{
			now = nx.front();
			nx.pop();

			//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);

				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;
}