Go: package main

import (
	"container/heap"
	"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)
	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)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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)
			}
		}
	}
	fmt.Println("NA")
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

C++: #include <bits/stdc++.h>

using namespace std;

struct People {
    int cnt;
    int tx, ty;
    int kx, ky;
};

int ans;
int X, Y;
int tx, ty;
int kx, ky;
int graph[50][50];
int check[50][50][50][50];
int vx[] = {0, 1, 0, -1};
int vy[] = {-1, 0, 1, 0};

int main() {

    while(cin >> X >> Y, X || Y) {

        ans = -1;
        memset(check, 0, sizeof(check));

        cin >> tx >> ty; tx--; ty--;
        cin >> kx >> ky; kx--; ky--;

        for(int i = 0; i < Y; ++i) {
            for(int j = 0; j < X; ++j) {
                cin >> graph[i][j];
            }
        }

        queue<People> q;
        q.push((People){0, tx, ty, kx, ky});
        check[tx][ty][kx][ky] = 1;

        while(!q.empty()) {

            People now = q.front(); q.pop();
            check[now.tx][now.ty][now.kx][now.ky] = 1;

            if(now.tx == now.kx && now.ty == now.ky) {
                if(now.cnt >= 100) {
                    break;
                }
                ans = now.cnt;
                break;
            }

            for(int i = 0; i < 4; ++i) {

                People next = now;
                next.cnt++;
                next.tx += vx[i];
                next.ty += vy[i];
                next.kx += vx[i] * -1;
                next.ky += vy[i] * -1;

                if( next.tx >= 0 && next.tx < X && next.ty >= 0 && next.ty < Y && !graph[next.ty][next.tx] &&
                    next.kx >= 0 && next.kx < X && next.ky >= 0 && next.ky < Y && !graph[next.ky][next.kx] &&
                    !check[next.tx][next.ty][next.kx][next.ky]) {

                    q.push(next);

                } else if(  next.tx >= 0 && next.tx < X && next.ty >= 0 && next.ty < Y && !graph[next.ty][next.tx] &&
                            (next.kx < 0 || next.kx >= X || next.ky < 0 || next.ky >= Y || graph[next.ky][next.kx]) && !check[next.tx][next.ty][now.kx]
[now.ky]) {

                    next.kx = now.kx;
                    next.ky = now.ky;
                    q.push(next);

                } else if(  next.kx >= 0 && next.kx < X && next.ky >= 0 && next.ky < Y && !graph[next.ky][next.kx] &&
                            (next.kx < 0 || next.kx >= X || next.ky < 0 || next.ky >= Y || graph[next.ky][next.kx]) && !check[now.tx][now.ty][next.kx][
next.ky]) {

                    next.tx = now.tx;
                    next.ty = now.ty;
                    q.push(next);

                }

            }

        }

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

    }

}

C++: #include<iostream>
#define M 52
#include<queue>
#include<cstring>
using namespace std;
struct P{
	int ax,ay,bx,by,cost;
	P(){}
	P(int h,int j,int k,int l,int co):
	ax(h),ay(j),bx(k),by(l),cost(co){}
	
};
int main(){
	bool s[M][M],d[M][M][M][M],u;
	int w,h,tx,ty,kx,ky,dx[]={1,-1,0,0},dy[]={0,0,-1,1};
	while(cin>>w>>h,w||h){
		cin>>tx>>ty;tx--;ty--;
		cin>>kx>>ky;kx--;ky--;
		for(int i=0;i<h;i++)
		for(int j=0;j<w;j++)
		cin>>s[i][j];
		queue<P> que;
		memset(d,sizeof(d),0);
		d[tx][ty][kx][ky]=1;
		que.push(P(tx,ty,kx,ky,0));
		u=true;
		while(!que.empty()){
			P p=que.front();
			que.pop();
			if(p.cost==100)
			break;
			if(p.ax==p.bx&&p.ay==p.by){
				cout<<p.cost<<endl;
				u=false;
				break;
			}
			int ntx,nty,nkx,nky;
			for(int i=0;i<4;i++){
				ntx=p.ax+dx[i];
				nty=p.ay+dy[i];
				nkx=p.bx-dx[i];
				nky=p.by-dy[i];
				if(!(ntx>=0&&ntx<w&&nty>=0&&nty<h)||s[nty][ntx]==1){
					ntx=tx;nty=ty;
				}
				if(!(nkx>=0&&nkx<w&&nky>=0&&nky<h)||s[nky][nkx]==1){
					nkx=kx;nky=ky;
				}
				if(d[ntx][nty][nkx][nky]!=1)
				que.push(P(ntx,nty,nkx,nky,p.cost+1));
				d[ntx][nty][nkx][nky]=1;
			}
		}
		if(u)
		cout<<"NA"<<endl;
	}
	return 0;
}

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

bool d[52][52][52][52];
int X, Y, tx, ty, kx, ky;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, mem[52][52];

int main()
{
loop:
  cin >> X >> Y;
  if(!X)
    return 0;
  cin >> tx >> ty >> kx >> ky;
  for(int y = 1; y <= Y; y++)
  {
    for(int x = 1; x <= X; x++)
    {
      int a;
      cin >> a;
      mem[y][x] = a;
    }
    mem[y][0] = 1;
    mem[y][X + 1] = 1;
  }
  for(int x = 0; x <= X + 1; x++)
  {
    mem[0][x] = 1;
    mem[Y + 1][x] = 1;
  }

  fill_n((bool*)d, 52 * 52 * 52 * 52, 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)
    {
      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(mem[ty1][tx1])
      {
        tx1 = x1;
        ty1 = y1;
      }
      if(mem[ty2][tx2])
      {
        tx2 = x2;
        ty2 = y2;
      }
      if(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;
}