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 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 <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> pip;
typedef pair<pii, pii> ppp;
typedef pair<int, ppp> P;
const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-9;

int W, H;
pii tp, kp;
int maps[50][50];
bool done[50][50][50][50];

int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};

bool ok(pii p) {
	if (!(p.fi >= 0 && p.fi < H && p.se >= 0 && p.se < W)) return false;
	if (maps[p.fi][p.se] == 1) return false;
	return true;
}

int main() {
	while (cin >> W >> H, W || H) {
		cin >> tp.se >> tp.fi >> kp.se >> kp.fi;
		tp.se--; tp.fi--; kp.se--; kp.fi--;
		REP(i, H) REP(j, W) scanf("%d", &maps[i][j]);
		
		memset(done, 0, sizeof(done));
		queue<P> que;
		que.push(P(0, ppp(tp, kp)));
		done[tp.fi][tp.se][kp.fi][kp.se] = true;
		
		int ans = INF;
		
		while (!que.empty()) {
			int c = que.front().fi;
			pii p1 = que.front().se.fi, p2 = que.front().se.se;
			que.pop();
			
			if (p1 == p2) { ans = c; break; }
			if (c >= 100) break;
			
			REP(i, 4) {
				pii np1(p1.fi + dy[i], p1.se + dx[i]);
				pii np2(p2.fi + dy[(i+2)%4], p2.se + dx[(i+2)%4]);
				
				bool o1 = ok(np1), o2 = ok(np2);
				if (!o1 && !o2) continue;
				
				np1 = o1 ? np1 : p1;
				np2 = o2 ? np2 : p2;
				if (!chmax(done[np1.fi][np1.se][np2.fi][np2.se], 1)) continue;
				que.push(P(c + 1, ppp(np1, np2)));
			}
		}
		
		if (ans == INF) puts("NA");
		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.ty][S.tx]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.ky][S.kx]==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<queue>
#include<map>
#include<cstring>
using namespace std;

struct node 
{
  int step;
  int tx,ty;
  int kx,ky;
  node(int s,int ttx,int tty,int kkx,int kky):
    step(s),tx(ttx),ty(tty),kx(kkx),ky(kky){} 
};
  
int main()
{
  int x,y;
  for(;cin>>x>>y,x;)
    {
      bool data[60][60];
      int tx,ty,kx,ky;
      cin>>tx>>ty>>kx>>ky;
      memset(data,false,sizeof(data));
      for(int i=1;i<=y;i++)
	for(int j=1;j<=x;j++)
	  {
	    char tmp;
	    cin>>tmp;
	    data[j][i]=(tmp=='0');
	  }
      queue<node> qu;
      qu.push(node(0,tx,ty,kx,ky));
      map< pair<pair<int,int>,pair<int,int> > ,bool >hash;
      int ans=-1;
      int dx[]={0,0,1,-1};
      int dy[]={1,-1,0,0};
      while(!qu.empty())
	{
	  node tmp=qu.front();
	  qu.pop();
	  //	  cout<<tmp.step<<" "<<tmp.tx<<" "<<tmp.ty<<" "<<tmp.kx<<" "<<tmp.ky<<endl;
	  if(hash[make_pair(make_pair(tmp.tx,tmp.ty),make_pair(tmp.kx,tmp.ky))])
	    continue;
	  if(tmp.tx==tmp.kx && tmp.ty==tmp.ky)
	    {
	      ans=tmp.step;
	      break;
	    }
	  if(tmp.step>=99)
	    continue;
	  hash[make_pair(make_pair(tmp.tx,tmp.ty),make_pair(tmp.kx,tmp.ky))]=true;
	  for(int i=0;i<4;i++)
	    {
	      int ttx=tmp.tx,tty=tmp.ty,tkx=tmp.kx,tky=tmp.ky;
	      if(data[ttx+dx[i]][tty+dy[i]])
		{
		  ttx+=dx[i];
		  tty+=dy[i];
		}
	      if(data[tkx-dx[i]][tky-dy[i]])
		{
		  tkx-=dx[i];
		  tky-=dy[i];
		}
	      //cout<<"make"<<ttx<<" "<<tkx<<" "<<tty<<" "<<tty<<endl;
	      if(!hash[make_pair(make_pair(ttx,tty),make_pair(tkx,tky))])
		qu.push(node(tmp.step+1,ttx,tty,tkx,tky));
	    }
	}
      if(ans==-1)
	cout<<"NA"<<endl;
      else
	cout<<ans<<endl;

    }
}