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<bits/stdc++.h>
using namespace std;
int main(){
  int W,H;
  int counter=0;
  int vxt[4]={1,0,-1,0};
  int vyt[4]={0,-1,0,1};
  int vxk[4]={-1,0,1,0};
  int vyk[4]={0,1,0,-1};
  while(cin>>W>>H,W+H!=0){
    int tx,ty,kx,ky;
    cin>>tx>>ty;
    cin>>kx>>ky;
    int ma[H+2][W+2];
    for(int i=0;i<H+2;i++)
      for(int j=0;j<W+2;j++)
	ma[i][j]=1;
    for(int i=1;i<H+1;i++)
      for(int j=1;j<W+1;j++)
	cin>>ma[i][j];
    queue<pair<pair<int,int>,int> >T;
    queue<pair<pair<int,int>,int> >K;
    T.push(make_pair(make_pair(tx,ty),0));
    K.push(make_pair(make_pair(kx,ky),0));
    bool flag=false;
    int ans;
    while(!(T.empty())||!(K.empty())){
      if(counter>=100){
	flag=true;
	break;
      }
      pair<pair<int,int>,int>nowt=T.front();
      pair<pair<int,int>,int>nowk=K.front();
      T.pop();K.pop();
      if(nowt.second==100||nowk.second==100){
	break;
      }
      if(nowt.second==nowk.second&&nowt.first.first==nowk.first.first&&
	 nowt.first.second==nowk.first.second){
	ans=nowt.second;
	flag=false;
	break;
      }
      for(int i=0;i<4;i++){
	if(ma[nowt.first.first+vxt[i]][nowt.first.second+vyt[i]]!=1)
	  T.push(make_pair(make_pair(nowt.first.first+vxt[i],nowt.first.second+vyt[i]),nowt.second+1));
	if(ma[nowk.first.first+vxk[i]][nowk.first.second+vyk[i]]!=1)
	  K.push(make_pair(make_pair(nowk.first.first+vxk[i],nowk.first.second+vyk[i]),nowk.second+1));
      }
      counter++;
    }
    if(flag)
      cout<<"NA"<<endl;
    else
      cout<<ans<<endl;
  }
  return 0;
}

C++: 

#include<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[52][52][52][52];
int main(){
	PP S;
	queue<PP> P;
	int  w,h;
	int d=0,i=0,j=0,l=-1,D[52][52];
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&w,&h);
	while(w!=0||h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1;
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			printf("%d\n",S.Z);
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;

		if(D[S.tx][S.ty]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.kx][S.ky]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

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

using namespace std;

const int inf = 999999;

struct P{
	int x;
	int y;
};

struct St{
	P tk;
	P kz;
	int cost;
};

int xdir[4] = {0, 1, 0, -1}, ydir[4] = {1, 0, -1, 0};

int bfs(char a[51][51], int w, int h, P p, P q)
{
	int r = inf;
	bool vis[51][51][51][51];
	fill(&vis[0][0][0][0], &vis[50][50][50][50], true);
	St s, t;
	queue<St> que;
	s.tk = p;
	s.kz = q;
	s.cost = 0;
	que.push(s);
	
	while(!que.empty()){
		s = que.front();
		que.pop();
		if(s.tk.x == s.kz.x && s.tk.y == s.kz.y){
			r = s.cost;
			break;
		}
		if(s.cost > 100){
			break;
		}
		
		for(int i = 0; i < 4; i++){
			int tx = s.tk.x+xdir[i], ty = s.tk.y+ydir[i];
			int kx = s.kz.x-xdir[i], ky = s.kz.y-ydir[i];
			if(0 <= tx && tx < w && 0 <= ty && ty < h && 0 <= kx && kx < w && 0 <= ky && ky < h){
				if(a[ty][tx] == '0' && a[ky][kx] == '0' && vis[ty][tx][ky][kx]){
					vis[ty][tx][ky][kx] = false;
					t.tk.x = tx;
					t.tk.y = ty;
					t.kz.x = kx;
					t.kz.y = ky;
					t.cost = s.cost+1;
					que.push(t);
				}
			}
		}
	}
	
	return r;
}

int main()
{
	int w, h, r;
	char a[51][51];
	P p, q;
	
	while(cin>>w>>h && (w+h)){
		cin >> p.x >> p.y;
		cin >> q.x >> q.y;
		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				cin >> a[i][j];
			}
		}
		
		r = bfs(a, w, h, p, q);
		if(r == inf){
			cout << "NA" << endl;
		} else {
			cout << r << endl;
		}
	}
	
	return 0;
}