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 ans <= now.Turn {
			continue
		}
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		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)
			}
		}
	}
	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<queue>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
using namespace std;
int dy[]={1,-1,0,0};
int dx[]={0,0,1,-1};
// 構造体
struct P{
  int ty;
  int tx;
  int ky;
  int kx;
  int c;
  P(int ty,int tx,int ky,int kx,int c):ty(ty),tx(tx),ky(ky),kx(kx),c(c){}
};
int bfs(int ty,int tx,int ky,int kx);
int g[51][51];
int d[51][51][51][51]; // フラグ
int x,y;
int main(){
  int tx,ty;
  int kx,ky;
  while(1){
    cin >> x >> y;
    if(!x && !y)break;
    cin >> tx >> ty;
  cin >> kx >> ky;
  for(int i=0;i<y;i++){
    for(int j=0;j<x;j++){
      cin >> g[i][j];
    }
  }
  int ret = bfs( ty - 1 , tx - 1 , ky - 1 , kx - 1 );
  if(ret != -1){
    cout << ret << endl;
  }else {
    cout << "NA" << endl;
  }
    memset( d , 0 , sizeof(d) );
  }
}
int bfs(int ty,int tx,int ky,int kx){
  queue<P> que;
  que.push(P(ty,tx,ky,kx,0));
  d[ty][tx][ky][kx] = 1;

  while(!que.empty()){
    P p = que.front();que.pop();
    // 終了判定
    if(p.c > 100)return -1;
    if(p.ty == p.ky && p.tx == p.kx)return p.c;
     for(int i=0;i<4;i++){
      int tty = p.ty + dy[i];
      int ttx = p.tx + dx[i];
      int kky = p.ky + (dy[i] * -1); // 　↓
      int kkx = p.kx + (dx[i] * -1); // 逆方向

      // 両方いけるとき
      if(0<=tty && tty<y && 0<=ttx && ttx<x){
        if(0<=kky && kky<y && 0<=kky && kkx<x){
          if(d[tty][ttx][kky][kkx] == 0  && g[tty][ttx] == 0 && g[kky][kkx] == 0){
            que.push(P(tty,ttx,kky,kkx,p.c+1));
            d[tty][ttx][kky][kkx] = 1;
          }
        }
      }
      // たかゆきくんだけいけるとき
      if(0<=tty && tty<y && 0<=ttx && ttx<x){
        if(0>kky || kky>=y || 0>kky || kkx>=x || g[kky][kkx] == 1){
          if(d[tty][ttx][p.ky][p.kx] == 0 && g[tty][ttx] == 0){
            que.push(P(tty,ttx,p.ky,p.kx,p.c+1));
            d[tty][ttx][p.ky][p.kx] = 1;
          }
        }
      }
      // 一之君だけいけるとき
       if(0<=kky && kky<y && 0<=kkx && kkx<x){
        if(0>tty || tty>=y || 0>tty || ttx>=x || g[tty][ttx] == 1){
          if(d[p.ty][p.tx][kky][kkx] == 0 && g[kky][kkx] == 0){
            que.push(P(p.ty,p.tx,kky,kkx,p.c+1));
            d[p.ty][p.tx][kky][kkx] = 1;
          }
        }
      }
    }
  }
  return -1;
}

C++: #include <queue>
#include <vector>
#include <iostream>

#define INF (1 << 25)

using namespace std;

vector<vector<vector<vector<int> > > > dp;

vector<vector<int> > M;

int H, W, sx1, sy1, sx2, sy2;

const int dx[4] = { 0, 1, 0, -1 };
const int dy[4] = { 1, 0, -1, 0 };

int bfs()
{
	dp = vector<vector<vector<vector<int> > > >(H, vector<vector<vector<int> > >(W, vector<vector<int> >(H, vector<int>(W, INF)))); dp[sy1][sx1][sy2][sx2] = 0;

	queue<pair<pair<pair<int, int>, pair<int, int> >, int> > que; que.push(make_pair(make_pair(make_pair(sx1, sy1), make_pair(sx2, sy2)), 0));

 	while (!que.empty())
	{
		int x1 = que.front().first.first.first;
		int y1 = que.front().first.first.second;
		int x2 = que.front().first.second.first;
		int y2 = que.front().first.second.second;

		int turn = que.front().second;

		que.pop();

		for (int dir = 0; dir < 4; dir++)
		{
			int tx1 = x1 + dx[dir]; if (tx1 < 0 || tx1 >= W) { tx1 -= dx[dir]; }
			int ty1 = y1 + dy[dir]; if (ty1 < 0 || ty1 >= H) { ty1 -= dy[dir]; }
			int tx2 = x2 - dx[dir]; if (tx2 < 0 || tx2 >= W) { tx2 += dx[dir]; }
			int ty2 = y2 - dy[dir]; if (ty2 < 0 || ty2 >= H) { ty2 += dy[dir]; }

			if (M[ty1][tx1] == 1) { tx1 -= dx[dir]; ty1 -= dy[dir]; }
			if (M[ty2][tx2] == 1) { tx2 += dx[dir]; ty2 += dy[dir]; }

			if (tx1 == tx2 && ty1 == ty2) { return turn + 1; }

			if (dp[ty1][tx1][ty2][tx2] == INF)
			{
				dp[ty1][tx1][ty2][tx2] = turn + 1;

				que.push(make_pair(make_pair(make_pair(tx1, ty1), make_pair(tx2, ty2)), turn + 1));
			}
		}
	}

	return -1;
}

int main()
{
	while (true)
	{
		cin >> W >> H;

		if (H == 0 && W == 0) { break; }

		M = vector<vector<int> >(H, vector<int>(W));

		cin >> sx1 >> sy1 >> sx2 >> sy2;

		sx1--; sy1--; sx2--; sy2--;

		for (int i = 0; i < H; i++)
		{
			for (int j = 0; j < W; j++)
			{
				cin >> M[i][j];
			}
		}

		int Ans = bfs();

		if (Ans == -1)
		{
			cout << "NA" << endl;
		}
		else
		{
			cout << Ans << endl;
		}
	}

	return 0;
}