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 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)
	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 len(pq) > 0 {
		now := &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 {
				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>
using namespace std;

const int INF=100000000;

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

int main(){
  while(true){
    int X,Y;
    cin>>X>>Y;
    if(X==0&&Y==0){
      break;
    }
    char F[50][50];
    int D[50][50];
    for(int x=1;x<=X;x++){
      for(int y=1;y<=Y;y++){
        D[x][y]=INF;
      }
    }
    int tx,ty;
    cin>>tx>>ty;
    int kx,ky;
    cin>>kx>>ky;
    D[tx][ty]=0;
    D[kx][ky]=0;

    for(int x=0;x<=X+2;x++){
      for(int y=0;y<=Y+2;y++){
        F[x][y]=1;
      }
    }
    int a;
    for(int x=1;x<=X;x++){
      for(int y=1;y<=Y;y++){
        cin>>a;
        F[x][y]=a;
      }
    }

    queue<Point> que;

    Point p;
    p.tx=tx;
    p.ty=ty;
    p.kx=kx;
    p.ky=ky;
    que.push(p);

    int b=1;
    while(!que.empty()||b>1000,b++){
      p=que.front();
      que.pop();

      if(p.tx==p.kx&&p.ty==p.ky){
        if(D[p.tx][p.ty]>100){
          cout<<"NA"<<endl;
          break;
        }
        cout<<D[p.tx][p.ty]<<endl;
        break;
      }

      if(D[p.tx-1][p.ty]==INF&&D[p.kx+1][p.ky]==INF){
        Point q;
        q.tx=p.tx-1;
        q.ty=p.ty;
        q.kx=p.kx+1;
        q.ky=p.ky;
        if(F[q.kx][q.ky]==1&&F[q.tx][q.ty]==1){
          q.kx=q.kx-1;
          q.tx=q.tx+1;
        }else
        if(F[q.tx][q.ty]==1){
          q.tx=q.tx+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.kx=q.kx-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }
        que.push(q);
      }

      if(D[p.tx+1][p.ty]==INF&&D[p.kx-1][p.ky]==INF){
        Point q;
        q.tx=p.tx+1;
        q.ty=p.ty;
        q.kx=p.kx-1;
        q.ky=p.ky;
        if(F[q.kx][q.ky]==1&&F[q.tx][q.ty]==1){
          q.kx=q.kx+1;
          q.tx=q.tx-1;
        }else
        if(F[q.tx][q.ty]==1){
          q.tx=q.tx-1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.kx=q.kx+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }
        que.push(q);
      }

      if(D[p.tx][p.ty+1]==INF&&D[p.kx][p.ky-1]==INF){
        Point q;

        q.tx=p.tx;
        q.ty=p.ty+1;
        q.kx=p.kx;
        q.ky=p.ky-1;
        que.push(q);
        if(F[q.kx][q.ky]==1&&F[q.tx][q.ty]==1){
          q.ky=q.ky+1;
          q.ty=q.ty-1;
        }else
        if(F[q.tx][q.ty]==1){
          q.ty=q.ty-1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.ky=q.ky+1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }
        que.push(q);
      }

      if(D[p.tx][p.ty-1]==INF&&D[p.kx][p.ky+1]==INF){
        Point q;
        q.tx=p.tx;
        q.ty=p.ty-1;
        q.kx=p.kx;
        q.ky=p.ky+1;
        if(F[q.kx][q.ky]==1&&F[q.tx][q.ty]==1){
          q.ky=q.ky-1;
          q.ty=q.ty+1;
        }else
        if(F[q.tx][q.ty]==1){
          q.ty=q.ty+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }else
        if(F[q.kx][q.ky]==1){
          q.ky=q.ky-1;
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
        }else{
          D[q.tx][q.ty]=D[p.tx][p.ty]+1;
          D[q.kx][q.ky]=D[p.kx][p.ky]+1;
        }
        que.push(q);
      }

    }
    if(b>500){
      cout<<"NA"<<endl;
    }
  }

  return 0;
}

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

const int INF = 100;
const int MAX = 50;
const int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
int field[MAX][MAX];
bool visited[MAX][MAX][MAX][MAX];

typedef pair<int, int> P;
typedef pair<P, P> Q;
typedef pair<int, Q> S;

bool check(int x, int y, int w, int h)
{
    return(x >= 0 && x < w && y >= 0 && y < h && field[y][x] == 0);
}

int main()
{
    int w, h, tx, ty, kx, ky;
    while(cin >> w >> h && w) {

        cin >> tx >> ty >> kx >> ky;
        for(int i = 0; i < h; i++) {
            for(int j = 0; j < w; j++) {
                cin >> field[i][j];
                for(int k = 0; k < h; k++) 
                    for(int l = 0; l < w; l++)
                        visited[i][j][k][l] = false;
            }
        }

        queue<S> que;
        int min = INF;
        que.push(S(0, Q( P(tx - 1, ty - 1), P(kx - 1, ky - 1))));
        while(!que.empty()) {
            S s = que.front(); que.pop();
            int x1, y1, x2, y2, step;
            step = s.first;
            x1 = s.second.first.first;
            y1 = s.second.first.second;
            x2 = s.second.second.first;
            y2 = s.second.second.second;
            
            if(x1 == x2 && y1 == y2) {
                min = step;
                break;
            }

            for(int k = 0; k < 4; k++) {
                int nx1, ny1, nx2, ny2;
                nx1 = x1 + dx[k];
                ny1 = y1 + dy[k];
                nx2 = x2 - dx[k];
                ny2 = y2 - dy[k];
                if(!check(nx1, ny1, w, h)) {
                    nx1 = x1;
                    ny1 = y1;
                }
                if(!check(nx2, ny2, w, h)) {
                    nx2 = x2;
                    ny2 = y2;
                }

                if(visited[nx1][ny1][nx2][ny2])
                    continue;
                visited[nx1][ny1][nx2][ny2] = true;
                que.push(S(step + 1, Q(P(nx1, ny1), P(nx2, ny2))));
            }
        }
        if(min == INF)
            cout << "NA" << endl;
        else 
            cout << min << endl;
    }
    
}