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 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)
			}
		}
	}
	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<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<queue>
#include<iostream>
using namespace std;
struct data{
    int x;
    int y;
    int u;
    int v;
    int t;
};

bool vis[60][60][60][60] = {};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
int main(void){
    int w,h;
    while(cin>>w>>h,w){
        int x,y,u,v;
        cin>>x>>y>>u>>v;
        bool screen[60][60] = {};
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin>>screen[i][j];
            }
        }
        data D;
        D.x = x,D.y = y;
        D.u = u,D.v = v;
        D.t = 0;
        queue<data> Q;
        Q.push(D);

        while(!Q.empty()){
            data E = Q.front();Q.pop();

            if(E.x == E.u&&E.y == E.v){
                cout<<E.t<<endl;
                goto e;
            }
            if(E.t>99)break;
            for(int i = 0;i < 4;i++){

                    data F = E;
                    F.t++;
                    F.x+=dx[i],F.y+=dy[i],F.u+=dx[(i+2)%4],F.v+=dy[(i+2)%4];
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h)){
                        F.x = E.x,F.y = E.y;
                    }
                    else if(screen[F.x][F.y])F.x = E.x,F.y = E.y;
                    if(!(0<=F.u&&F.u<w&&0<=F.v&&F.v<h)){
                        F.u = E.u,F.v = E.v;
                    }
                    else if(screen[F.u][F.v])F.u = E.u,F.v = E.v;
                    if(!vis[F.x][F.y][F.u][F.v]&&!vis[F.u][F.v][F.x][F.y]){

                        vis[F.x][F.y][F.u][F.v] = true;
                        vis[F.u][F.v][F.x][F.y] = true;
                        Q.push(F);
                    }

            }

        }
        cout<<"NA"<<endl;
        e:;
    }


    return 0;
}

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

const int INF =100000000;

class Point{
public:
  int tx;
  int ty;
  int kx;
  int ky;
};

int main(){
  while(1){
      int N,M;
      cin>>N>>M;
      if(N==0&&M==0)return 0;
      int o_tx,o_ty;
      int o_kx,o_ky;
      cin>>o_tx>>o_ty;
      cin>>o_kx>>o_ky;
      int F[52][52];
      for(int y=0;y<=N+1;y++){
        for(int x=0;x<=M+1;x++){
          F[y][x]=1;
        }
      }

      for(int y=1;y<=N;y++){
        for(int x=1;x<=M;x++){
          cin>>F[y][x];
        }
      }

      int D[52][52];
      for(int y=1;y<=N;y++){
        for(int x=1;x<=M;x++){
          D[y][x]=INF;
        }
      }
      bool same_pos[52][52][52][52];
      for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
          for(int k=1;k<=N;k++){
            for(int q=1;q<=M;q++){
              same_pos[i][j][k][q]=false;
            }
          }
        }
      }
      queue<Point> que;
      Point p;
      p.tx=o_tx;p.ty=o_ty;
      p.kx=o_kx;p.ky=o_ky;
      que.push(p);
      D[p.ty][p.tx]=0;

      while(!que.empty()){
        p=que.front();que.pop();
        if(same_pos[p.ty][p.tx][p.ky][p.kx])continue;
        same_pos[p.ty][p.tx][p.ky][p.kx]=true;
        if(D[p.ty][p.tx]>=100)break;
        if(p.tx==p.kx&&p.ty==p.ky){
          cout<<D[p.ty][p.tx]<<endl;
          break;
        }
        if(F[p.ty-1][p.tx]!=1 || F[p.ky+1][p.kx]!=1){
          Point q;
          if(F[p.ty-1][p.ty]!=1){
            q.tx=p.tx;q.ty=p.ty-1;
          }
          if(F[p.ky+1][p.kx]!=1){
            q.kx=p.kx;q.ky=p.ky+1;
          }
          que.push(q);
          D[q.ty][q.tx]=D[p.ty][p.tx]+1;

        }
        if(F[p.ty+1][p.tx]!=1 || F[p.ky-1][p.kx]!=1){
          Point q;
          if(F[p.ty+1][p.tx]!=1){
            q.tx=p.tx;q.ty=p.ty+1;
          }
          if(F[p.ky-1][p.kx]!=1){
            q.kx=p.kx;q.ky=p.ky-1;
          }
          que.push(q);
          D[q.ty][q.tx]=D[p.ty][p.tx]+1;
        }
        if(F[p.ty][p.tx-1]!=1 || F[p.ky][p.kx+1]!=1){
          Point q;
          if(F[p.ty][p.tx-1]!=1){
            q.tx=p.tx-1;q.ty=p.ty;
          }
          if(F[p.ky][p.kx+1]!=1){
            q.kx=p.kx+1;q.ky=p.ky;
          }
          que.push(q);
          D[q.ty][q.tx]=D[p.ty][p.tx]+1;
        }
        if(F[p.ty][p.tx+1]!=1 || F[p.ky][p.kx-1]!=1){
          Point q;
          if(F[p.ty][p.tx+1]!=1){
            q.tx=p.tx+1;q.ty=p.ty;
          }
          if(F[p.ky][p.kx-1]!=1){
            q.kx=p.kx-1;q.ky=p.ky;
          }
          que.push(q);
          D[q.ty][q.tx]=D[p.ty][p.tx]+1;
        }
      }
      if(p.tx!=p.kx || p.ty!=p.ky){
        cout<<"NA\n";
      }
    }
  return 0;
}