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
		}
		if ans<=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<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<string>

using namespace std;

#define rep(i,n) for(int i=0;i<int(n);i++)
#define reps(i,n) for(int i=1;i<=int(n);i++)
#define sint(i) scanf("%d",&i);
#define sintt(i,j) scanf("%d%d",&i,&j);
#define sinttt(i,j,k) scanf("%d%d%d",&i,&j,&k);
#define sintttt(i,j,k,m) scanf("%d%d%d%d",&i,&j,&k,&m);

#define INF 1010000000
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};

class S{
	public:
	int a,b,c,d;
	int n;
	S(int p,int n,int t,int k,int i):a(p),b(n),c(t),d(k),n(i){}
	
};

char visit[51][51][51][51];

int main(){
	while(1){
		int n,m;
		sintt(n,m);
		if(n==0)break;
		int a,b,c,d;
		sintttt(a,b,c,d);
		
		int masu[51][51];
		
		rep(i,51)rep(j,51)masu[j][i]=0;
		reps(i,m){
			reps(j,n){
				sint(masu[j][i]);
			}
		}
		
		queue<S> que;
		que.push(S(a,b,c,d,0));
		rep(i,51)rep(j,51)rep(k,51)rep(p,51)visit[i][j][k][p]=0;
		int ans=0;
		while(1){
			if(que.empty()==1){
				break;
			}
			
			
			S u=que.front();
			que.pop();
			
			//printf("%d %d  %d %d  %d\n",u.a,u.b,u.c,u.d,u.n);
			
			if(visit[u.a][u.b][u.c][u.d]==1){
				continue;
			}
			visit[u.a][u.b][u.c][u.d]=1;
			
			if(u.a==u.c && u.b==u.d){
				ans=u.n;
				break;
			}
			
			rep(i,4){
				int dx1=u.a+dx[i];
				int dy1=u.b+dy[i];
				
				int dx2=u.c+dx[i]*-1;
				int dy2=u.d+dy[i]*-1;
				
				//printf("push %d %d %d %d\n",dx1,dy1,dx2,dy2);
				
				if(dx1<=0 || dy1<=0 || dx1>n ||dy1>m|| masu[dx1][dy1]==1){
					dx1-=dx[i];
					dy1-=dy[i];
				}
				if(dx2<=0 || dy2<=0 || dx2>n ||dy2>m|| masu[dx2][dy2]==1){
					dx2-=dx[i]*-1;
					dy2-=dy[i]*-1;
				}
				
				//printf("push %d %d %d %d\n",dx1,dy1,dx2,dy2);
				que.push(S(dx1,dy1,dx2,dy2,u.n+1));
			}
		}
		if(ans==0){
			puts("NA");
		}else{
			printf("%d\n",ans);
		}
	}
}

C++: #include<iostream>
#include<queue>
#include<cstring>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int w,h;
PP S;
bool A[53][53][53][53],D[53][53];
int main(){
	queue<PP> P;
	int d=0,i=0,j=0,l=-1;
	int tx[4]={ 1, 0,-1,0 };       
	int ty[4]={ 0, 1, 0,-1 };
	cin>>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;
			}
		}

		cin>>S.tx>>S.ty;
		cin>>S.kx>>S.ky;
		for(i=1;i<=h;i++){
			for(j=1;j<=w;j++){
				cin>>D[i][j];
			}
		}
		S.Z=0;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			cout<<S.Z<<endl;
		}
		while(d!=-1){
			l++;
			S=P.front();
			if(l==4){
				l=0;
				P.pop();
				if(P.empty()){
					cout<<"NA"<<endl;
					break;
				}
			}

			S.tx=S.tx+tx[l];
			S.ty=S.ty+ty[l];
			S.kx=S.kx+tx[l]*-1;
			S.ky=S.ky+ty[l]*-1;
			if(A[S.ty][S.tx][S.ky][S.kx]==1||(D[S.ty][S.tx]==1&&D[S.ky][S.kx]==1)){
				continue;
			}
			A[S.ty][S.tx][S.ky][S.kx]=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-tx[l]*-1;
				S.ky=S.ky-ty[l]*-1;
			}
			//saka();
			S.Z++;
			P.push(S);
			if(S.tx==S.kx&&S.ty==S.ky){
				cout<<S.Z<<endl;
				break;
			}	
			if(S.Z==100){
				cout<<"NA"<<endl;
				break;
			}


		}
		while(!P.empty()){
			P.pop();
		}
		d=0;
		l=-1;
		cin>>w>>h;
	}	
	return 0;
}

C++: #include<cstring>
#include<cstdlib>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
using namespace std;


struct S{
  S(){};
  int tx,ty,kx,ky;
};
int X,Y;
S s;
vector<vector<int> > f;

bool input(){
  f.clear();
  s=S();
  cin>>X>>Y;
  if(X==0&&Y==0)return false;
  cin>>s.tx>>s.ty;
  cin>>s.kx>>s.ky;
  swap(s.tx,s.ty);
  swap(s.kx,s.ky);
  vector<int> kabe;
  for(int i=0;i<X+2;i++){
    kabe.push_back(1);
  }
  f.push_back(kabe);
  for(int i=0;i<Y;i++){
    vector<int> tt;
    tt.push_back(1);
    for(int j=0;j<X;j++){
      int tmp;
      cin>>tmp;
      tt.push_back(tmp);
    }
    tt.push_back(1);
    f.push_back(tt);
  }
  f.push_back(kabe);
  return true;
}

int vx[]={0,0,1,-1};
int vy[]={1,-1,0,0};
int used[60][60][60][60];
queue<S> q;
int bfs(S pos){
  memset(used,-1,(60*60*60*60));
  q = queue<S>();
  q.push(pos);
  used[pos.tx][pos.ty][pos.kx][pos.ky]=0;
  while(!q.empty()){
    S now = q.front();q.pop();
    if(used[now.tx][now.ty][now.kx][now.ky]>=100){
      return -1;
    }
    if(now.tx==now.kx&&now.ty==now.ky){
      return used[now.tx][now.ty][now.kx][now.ky];
    }
    for(int i=0;i<4;i++){
      S tmp = now;
      bool a,b;
      if(a=(f[tmp.tx+vx[i]][tmp.ty+vy[i]]!=1)){
        tmp.tx += vx[i];
        tmp.ty += vy[i];
      }
      if(b=(f[tmp.kx-vx[i]][tmp.ky-vy[i]]!=1)){
        tmp.kx -= vx[i];
        tmp.ky -= vy[i];
      }
      if((!(a||b))||(used[tmp.tx][tmp.ty][tmp.kx][tmp.ky]!=-1)){
        continue;
      }
      used[tmp.tx][tmp.ty][tmp.kx][tmp.ky]=used[now.tx][now.ty][now.kx][now.ky]+1;
      q.push(tmp);
    }
  }
  return -1;
}

int solve(){
  return bfs(s);
}

int main(){
  while(input()){
    int ans = solve();
    if(ans>=0){
      cout<<ans<<endl;
    }else{
      cout<<"NA"<<endl;
    }
  }
}