Go: package main

import (
	"container/heap"
	"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)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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)
			}
		}
	}
	fmt.Println("NA")
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

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

#define rep(i,n) for(int i=0;i<n;i++) 

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

class NODE{
public:
	int x1;
	int y1;
	int x2;
	int y2;
	int depth;
};

int main(){
	int X,Y,tx,ty,kx,ky;
	bool data[52][52];
	while(cin >> X >> Y , X){
		cin >> tx >> ty >> kx >> ky;
		rep(i,52)rep(j,52)data[i][j] = 1;
		rep(i,Y)rep(j,X){
			cin >> data[1+i][1+j];
		}
		queue<NODE> Q;
		NODE t = {tx,ty,kx,ky,0};
		Q.push(t);
		bool done[52][52][52][52] = {0};
		while(Q.size()){
			NODE q = Q.front();Q.pop();
			if(q.depth >= 100)continue;
			if( done[q.x1][q.y1][q.x2][q.y2] )continue;
			done[q.x1][q.y1][q.x2][q.y2] = true;
			
			if(q.x1 == q.x2 && q.y1 == q.y2){
				cout << q.depth << endl;
				goto end;
			}
			rep(i,4){
				NODE next;
				next.x1 = q.x1 + dx[i];
				next.y1 = q.y1 + dy[i];
				next.x2 = q.x2 - dx[i];
				next.y2 = q.y2 - dy[i];
				next.depth = q.depth + 1;
				if(data[next.y1][next.x1] == 1){
					next.x1 = q.x1;
					next.y1 = q.y1;
				}
				if(data[next.y2][next.x2] == 1){
					next.x2 = q.x2;
					next.y2 = q.y2;
				}
				Q.push(next);
			}
		}
		cout << "NA" << endl;
		end:;	
	}
}

C++: #include <cstdio>
#include <utility>
#include <queue>
#include <map>
using namespace std;

typedef pair<int,int> __P;
typedef pair<__P,__P> _P;
typedef pair<_P,int> P;

#define C(A,B) (0<=(A)&&(A)<(B))

int main() {
	queue<P> que;
	map<P,bool> mp;
	int X,Y;
	int tx,ty;
	int kx,ky;
	int count;
	int d[50][50];
	int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
	while(true) {
		scanf("%d %d",&X,&Y);
		if(X==0&&Y==0) break;
		scanf("%d %d",&tx,&ty);
		scanf("%d %d",&kx,&ky);
		tx--;ty--;kx--;ky--;
		for(int i=0;i<Y;i++) {
			for(int j=0;j<X;j++) {
				scanf("%d",&d[j][i]);
			}
		}
		que.push(P(_P(__P(tx,ty),__P(kx,ky)),0));
		count=-1;
		while(que.size()) {
			P& p=que.front();
			tx=p.first.first.first;
			ty=p.first.first.second;
			kx=p.first.second.first;
			ky=p.first.second.second;
			if(p.second>=100) {
				break;
			}
			if(mp[p]==true) {
				break;
			}
			if(tx==kx&&ty==ky) {
				count=p.second;
				break;
			}
			mp[p]=true;
			for(int i=0;i<4;i++) {
				int ntx=tx,nty=ty,nkx=kx,nky=ky;
				if(C(ntx+dx[i],X)&&C(nty+dy[i],Y)&&!d[ntx+dx[i]][nty+dy[i]]) {
					ntx+=dx[i],nty+=dy[i];
				}
				if(C(nkx-dx[i],X)&&C(nky-dy[i],Y)&&!d[nkx-dx[i]][nky-dy[i]]) {
					nkx-=dx[i],nky-=dy[i];
				}
				que.push(P(_P(__P(ntx,nty),__P(nkx,nky)),p.second+1));
			}
			
			que.pop();
		}
		if(count!=-1) {
			printf("%d\n",count);
		}else {
			printf("NA\n");
		}
	}
}

C++: #include <algorithm>
#include <map>
#include <vector>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstring>
#include <cctype>
#include <cstdlib>
#include <cmath>
#include <string>
#include <queue>
#include <stack>
#include <set>
#define r(i,n) for(int i=0;i<n;i++)
using namespace std;
#define mk make_pair
#define f first
#define s second
typedef pair<int,int> P;
int a[51][51],ax,bx,ay,by;
int dx1[]={1,0,-1,0};
int dy1[]={0,1,0,-1};
int dx2[]={-1,0,1,0};
int dy2[]={0,-1,0,1};
bool used[10000000];
int gethash(P q,P w){
  return q.f+q.s*52+w.f*52*52+w.s*52*52*52;
}
int main(){
  int w,h;
  while(cin>>w>>h,w){
    memset(used,0,sizeof(used));
    cin>>ax>>ay>>bx>>by;ax--,ay--,bx--,by--;
    r(i,h)r(j,w)cin>>a[i][j];
    used[gethash(P(ay,ax),P(by,bx))]=1;
    queue<pair<int,pair<pair<int,int>,pair<int,int> > > >q;
    q.push(mk(0,mk(mk(ay,ax),mk(by,bx))));
    while(!q.empty()){
      pair<int,pair<pair<int,int>,pair<int,int> > >p=q.front();q.pop();
      P p1=p.s.f,p2=p.s.s;
      if(p1==p2){
	cout<<p.f<<endl;
	goto L;
      }
      r(i,4){
	int x1=p1.s+dx1[i],x2=p2.s+dx2[i],y1=p1.f+dy1[i],y2=p2.f+dy2[i];
	if(x1<0||x1>=w)x1=p1.s;
	if(x2<0||x2>=w)x2=p2.s;
	if(y1<0||y1>=h)y1=p1.f;
	if(y2<0||y2>=h)y2=p2.f;
	if(a[y1][x1])x1=p1.s,y1=p1.f;
	if(a[y2][x2])x2=p2.s,y2=p2.f;
	if(!used[gethash(P(y1,x1),P(y2,x2))]){
	  used[gethash(P(y1,x1),P(y2,x2))]=1;
	  q.push(mk(p.f+1,mk(mk(y1,x1),mk(y2,x2))));
	}
      }
    }
    cout<<"NA"<<endl;L:;
  }
}