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 ans <= now.Turn {
			continue
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = 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>
#include<map>
using namespace std;
const int INF=(1<<21);
typedef pair<int,int> P;
int x,y;
int tx,ty;
int kx,ky;
int t_check[50][50];
int k_check[50][50];
int depart[50][50];
int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int ans=0;

int bfs(){
  queue<P> t_que;
  queue<P> k_que;

  for(int i=0;i<y;i++){
    for(int j=0;j<x;j++){
      t_check[i][j]=k_check[i][j]=INF;
    }
  }

  t_check[ty][tx]=0;
  k_check[ky][kx]=0;

  t_que.push(P(ty,tx));
  k_que.push(P(ky,kx));

  while(t_que.size()){
    P tp=t_que.front();t_que.pop();
    P kp=k_que.front();k_que.pop();
    if(tp.first==kp.first && tp.second==kp.second){
      return t_check[tp.first][tp.second];
    }

    for(int i=0;i<4;i++){
      int tnx=tp.second+dx[i];
      int tny=tp.first+dy[i];
      int knx=kp.second-(dx[i]);
      int kny=kp.first-(dy[i]);

      if(0<=tnx && tnx<x && 0<=tny && tny<y && depart[tny][tnx]!=1 && t_check[tny][tnx]==INF  &&  0<=knx && knx<x && 0<=kny && kny<y && depart[kny][knx]!=1 && k_check[kny][knx]==INF){

	t_que.push(P(tny,tnx));
	k_que.push(P(kny,knx));
	t_check[tny][tnx]=t_check[tp.first][tp.second]+1;
	k_check[kny][knx]=k_check[kp.first][kp.second]+1;

      }
    }
  }
  return -1;
}
int main(){
  while(1){
    cin>> x>> y;
  if(x==0 && y==0){
    break;
  }
  cin>> tx>> ty;
  cin>> kx>> ky;
  for(int i=0;i<y;i++){
    for(int j=0;j<x;j++){
      cin>> depart[i][j];
    }
  }
  ans=bfs();
  if(ans==-1){
    cout<< "NA"<<endl;
  }else{
    cout<< ans<< endl;
  }
  }
}

C++: #include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

const int MAX = 50;
const int INF = (1<<25);

int come[MAX][MAX][MAX][MAX];
int M[MAX][MAX];
int w,h,stx,sty,skx,sky;
int dx[] = {1,-1,0,0};
int dy[] = {0,0,1,-1};
void init(){
  //fill(come[0][0][0],come[0][0][0]+MAX*MAX*MAX*MAX,INF);
  memset(come,-1,sizeof(come));
}

void input(){
  cin >> stx >> sty >> skx >> sky;
  for(int i = 0; i < h; i++)
    for(int j = 0; j < w; j++) cin >> M[i][j];
}

bool isMovable(int x, int y){return 0<=x&&x<w&&0<=y&&y<h&&M[y][x]==0;}
void dfs(int t, int tx, int ty, int kx, int ky){

  if(t > 100 || come[tx][ty][kx][ky] <= t && come[tx][ty][kx][ky] != -1) return;
  come[tx][ty][kx][ky] = t;

  for(int i = 0; i < 4; i++){
    int ntx = tx+dx[i];
    int nty = ty+dy[i];
    int nkx = kx-dx[i];
    int nky = ky-dy[i];

    int move = 0;
    if(!isMovable(ntx,nty)){
      ntx = tx;
      nty = ty;
      move++;
    }
    if(!isMovable(nkx,nky)){
      nkx = kx;
      nky = ky;
      move++;
    }
    if(move == 2) return;

    dfs(t+1,ntx,nty,nkx,nky);
  }
}

void solve(){
  dfs(0,stx,sty,skx,sky);
  
  int ans = INF;
  for(int i = 0; i < w; i++)
    for(int j = 0; j < h; j++)
      if(come[i][j][i][j] != -1) ans = min(ans,come[i][j][i][j]);

  if(ans == INF) cout << "NA" << endl;
  else cout << ans << endl;
}

int main(){
  while(cin >> w >> h && w+h){
    init();
    input();
    solve();
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef tuple<int, int, int, int, int> T;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int main() {
    while (true) {
        int W, H;
        cin >> W >> H;
        
        if (W==0 && H==0) {
            break;
        }
        
        int tx, ty;
        cin >> tx >> ty;
        tx -= 1;
        ty -= 1;
        
        int kx, ky;
        cin >> kx >> ky;
        kx -= 1;
        ky -= 1;
        
        int d[H][W];
        
        for (int i=0; i<H; i++) {
            for (int j=0; j<W; j++) {
                cin >> d[i][j];
            }
        }
        
        int visited[H][W][H][W];
        
        for (int i=0; i<H; i++) {
            for (int j=0; j<W; j++) {
                for (int k=0; k<H; k++) {
                    for (int l=0; l<W; l++) {
                        visited[i][j][k][l] = -1;
                    }
                }
            }
        }
        
        queue<T> q;
        q.push(make_tuple(ty, tx, ky, kx, 0));
        
        bool flag = false;
        
        while (q.size()) {
            T t = q.front(); q.pop();
            int i1 = get<0>(t);
            int j1 = get<1>(t);
            int i2 = get<2>(t);
            int j2 = get<3>(t);
            int cost = get<4>(t);
            
            if (cost==100) {
                continue;
            }
            
            if (i1==i2 && j1==j2) {
                cout << cost << endl;
                flag = true;
                break;
            }
            
            for (int i=0; i<4; i++) {
                int ni1 = i1+dx[i];
                int nj1 = j1+dy[i];
                int ni2 = i2-dx[i];
                int nj2 = j2-dy[i];
                
                if (!(0<=ni1 && ni1<H && 0<=nj1 && nj1<W)) {
                    ni1 = i1;
                    nj1 = j1;
                }
                else if (d[ni1][nj1]==1) {
                    ni1 = i1;
                    nj1 = j1;
                }
                
                if (!(0<=ni2 && ni2<H && 0<=nj2 && nj2<W)) {
                    ni2 = i2;
                    nj2 = j2;
                }
                else if (d[ni2][nj2]==1) {
                    ni2 = i2;
                    nj2 = j2;
                }
                
                if (visited[ni1][nj1][ni2][nj2]==-1) {
                    visited[ni1][nj1][ni2][nj2] = 1;
                    q.push(make_tuple(ni1, nj1, ni2, nj2, cost+1));
                }
            }
        }
        
        if (flag) {
            continue;
        }
        
        cout << "NA" << endl;
    }
}