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(102)
	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++
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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 <iostream>
#include <queue>
#include <cstring>
using namespace std;


int H,W;
bool F[52][52]; //障害物
bool D[52][52][52][52]; //探索済みかの判定用
int inc_tx[4] = {1,-1,0,0};
int inc_ty[4] = {0,0,1,-1};
int inc_kx[4] = {-1,1,0,0};
int inc_ky[4] = {0,0,-1,1};

class Point{
public:
  int tx; //タカユキの座標
  int ty;
  int kx; //カズユキの座標
  int ky;
  int d; //ターン回数
  void set(int a,int b,int c,int d){
    tx = a;
    ty = b;
    kx = c;
    ky = d;
  }
};

bool is_out_of_area(int y,int x) //座標が範囲内か確認する関数
{
  return x < 1 || x > W || y < 1 || y > H || F[y][x];
}

int main(){

  while(1){

    Point p,q;
    int tx,ty,kx,ky;
    queue<Point> qa;
    cin >> W >> H;
    if(W == 0 && H == 0)
    break;
    cin >> tx >> ty >> kx >> ky;
    memset(F,1,sizeof(F));
    for(int y=1;y<=H;y++){
      for(int x=1;x<=W;x++){
        cin >> F[y][x];
      }
    }
    memset(D,1,sizeof(D));
    p.set(tx,ty,kx,ky);
    D[ty][tx][ky][kx] = 0;
    p.d = 0;
    qa.push(p);
    while(1){
      if(qa.empty()){
        cout << "NA" <<endl;
        break;
      }
      p = qa.front();
      qa.pop();
      if(p.d >= 100){
        cout << "NA" << endl;
        break;
      }
      if(p.tx == p.kx && p.ty == p.ky){
        cout << p.d << endl;
        break;
      }
      for(int i=0;i<4;i++){
        q.tx = p.tx + inc_tx[i]; q.ty = p.ty + inc_ty[i];
        q.kx = p.kx + inc_kx[i]; q.ky = p.ky + inc_ky[i];
        if(D[q.ty][q.tx][q.ky][q.kx]){
          if(is_out_of_area(q.ty ,q.tx) == 0 || is_out_of_area(q.ky ,q.kx) == 0){
            if(is_out_of_area(q.ty ,q.tx)){
              q.ty = p.ty; q.tx = p.tx;
            }
            if(is_out_of_area(q.ky ,q.kx)){
              q.ky = p.ky; q.kx = p.kx;
            }
            q.d = p.d + 1;
            qa.push(q);
            D[q.ty][q.tx][q.ky][q.kx] = 0;
          }
        }
      }
    }
  }
  return 0;
}

C++: #include <queue>
#include <vector>
#include <cstring>
#include <iostream>
using namespace std;
int H, W, ax, ay, bx, by, x[52][52], dp[52][52][52][52];
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
int main() {
	while(cin >> W >> H >> ax >> ay >> bx >> by) {
		for(int i = 0; i < H + 2; i++) {
			for(int j = 0; j < W + 2; j++) {
				x[i][j] = 1;
				if(i && i != H + 1 && j && j != W + 1) cin >> x[i][j];
			}
		}
		memset(dp, -1, sizeof(dp)); dp[ay][ax][by][bx] = 0;
		queue<vector<int> > que; que.push({ax, ay, bx, by});
		bool flag = false;
		while(!que.empty()) {
			vector<int> v1 = que.front(); que.pop();
			for(int i = 0; i < 4; i++) {
				vector<int> v2 = v1;
				if(!x[v1[1] + dy[i]][v1[0] + dx[i]]) v2[0] += dx[i], v2[1] += dy[i];
				if(!x[v1[3] - dy[i]][v1[2] - dx[i]]) v2[3] -= dx[i], v2[2] -= dy[i];
				if(v2[0] == v2[2] && v2[1] == v2[3]) {
					flag = true; break;
				}
				if(dp[v2[1]][v2[0]][v2[3]][v2[2]] == -1) {
					dp[v2[1]][v2[0]][v2[3]][v2[2]] = dp[v1[1]][v1[0]][v1[3]][v1[2]] + 1;
				}
			}
			if(flag) cout << dp[v1[1]][v1[0]][v1[3]][v1[2]] + 1 << endl;
		}
		if(!flag) cout << "NA" << endl;
	}
}

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

bool d[50][50][50][50];
int X, Y, tx, ty, kx, ky;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, mem[50][50];

bool _check(int x, int y)
{
  return x >= 0 && x < X && y >= 0 && y < Y;
}

bool check(int x1, int y1, int x2, int y2)
{
  return _check(x1, y1) && _check(x2, y2);
}

int main()
{
loop:
  cin >> X >> Y;
  if(!X)
    return 0;
  cin >> tx >> ty >> kx >> ky;
  tx--; ty--; kx--; ky--;
  for(int y = 0; y < Y; y++)
  {
    for(int x = 0; x < X; x++)
    {
      int a;
      cin >> a;
      mem[y][x] = a;
    }
  }

  fill_n((bool*)d, 50 * 50 * 50 * 50, false);
  
  queue<int> q;
  q.push(tx);
  q.push(ty);
  q.push(kx);
  q.push(ky);
  q.push(0);
  while(!q.empty())
  {
    int x1 = q.front(); q.pop();
    int y1 = q.front(); q.pop();
    int x2 = q.front(); q.pop();
    int y2 = q.front(); q.pop();
    int n = q.front(); q.pop();
    
    if(n >= 100)
    {
      cout << "NA" << endl;
      break;
    }
    
    if(y1 == y2 && x1 == x2)
    {
      cout << n << endl;
      goto loop;
    }

    for(int i = 0; i < 4; i++)
    {
      int tx1 = x1 + dx[i];
      int ty1 = y1 + dy[i];
      int tx2 = x2 - dx[i];
      int ty2 = y2 - dy[i];

      if(check(tx1, ty1, tx2, ty2) && mem[ty1][tx1] && !mem[ty2][tx2])
      {
        tx1 = x1;
        ty1 = y1;
      }
      if(check(tx1, ty1, tx2, ty2) && mem[ty2][tx2] && !mem[ty1][tx1])
      {
        tx2 = x2;
        ty2 = y2;
      }
      if(!check(tx1, ty1, tx2, ty2) || d[tx1][ty1][tx2][ty2])
        continue; 

      d[tx1][ty1][tx2][ty2] = true;
      q.push(tx1);
      q.push(ty1);
      q.push(tx2);
      q.push(ty2);
      q.push(n + 1);
    }
  }
  cout << "NA" << endl;
  goto loop;
}