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<algorithm>
#include<vector>
#include<stack>
#include<map>
#include<set>
#include<queue>
#include<cstdio>
#include<climits>
#include<cmath>
#include<cstring>
#include<string>
#include<sstream>
#include<numeric>
#include<cassert>

#define f first
#define s second
#define mp make_pair

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define rep(i,s,n) for(int i=(s); i<(int)(n); i++)
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin(); i!=(c).end(); i++)
#define ALL(c) (c).begin(), (c).end()
#define IN(x,s,g) ((x) >= (s) && (x) < (g))
#define ISIN(x,y,w,h) (IN((x),0,(w)) && IN((y),0,(h)))
#define print(x) printf("%d\n",x)

using namespace std;

typedef unsigned int uint;
typedef long long ll;

const int _dx[] = {0,1,0,-1};
const int _dy[] = {-1,0,1,0};

int getInt(){
  int ret = 0,c;
  c = getchar();
  while(!isdigit(c)) c = getchar();
  while(isdigit(c)){
    ret *= 10;
    ret += c - '0';
    c = getchar();
  }
  return ret;
}

int memo[52][52][52][52];

int main(){
  int w,h;
  while((w = getInt()) + (h = getInt())){
    int tx = getInt();
    int ty = getInt();
    int kx = getInt();
    int ky = getInt();

    w += 2; h += 2;
    vector<vector<int> > m(h, vector<int>(w, 1));

    REP(i,h-2) REP(j,w-2)
      m[i+1][j+1] = getInt();

    //REP(i,h){ REP(j,w) printf("%d ",m[i][j]); puts(""); }

    memset(memo, -1, sizeof(memo));

    typedef pair<pair<int,int>,pair<int,int> > data;
    queue<data> q;

#define MP(a,b,c,d) mp(mp(a,b),mp(c,d))
    q.push(MP(tx,ty,kx,ky));
    memo[tx][ty][kx][ky] = 0;

    while(!q.empty()){
      data d = q.front();

      int txx = d.f.f;
      int tyy = d.f.s;
      int kxx = d.s.f;
      int kyy = d.s.s;

      int now = memo[txx][tyy][kxx][kyy];

      if(now == 100){
        puts("NA");
        break;
      }
      if(txx == kxx && tyy == kyy){
        printf("%d\n",memo[txx][tyy][kxx][kyy]);
        break;
      }

      //printf("%d,%d : %d,%d\n",txx,tyy,kxx,kyy);
      q.pop();

      REP(i,4){
        int txxx = txx + _dx[i];
        int tyyy = tyy + _dy[i];

        int kxxx = kxx - _dx[i];
        int kyyy = kyy - _dy[i];

        if(m[tyyy][txxx] == 1){
          txxx = txx;
          tyyy = tyy;
        }

        if(m[kyyy][kxxx] == 1){
          kxxx = kxx;
          kyyy = kyy;
        }

        if(memo[txxx][tyyy][kxxx][kyyy] == -1){
          memo[txxx][tyyy][kxxx][kyyy] = now + 1;
          q.push(MP(txxx,tyyy,kxxx,kyyy));
        }
      }
    }
    if(q.empty()){
      puts("NA");
    }
  }
  return 0;
}

C++: #include<cstdio>
#include<iostream>
#include<string>
#include<map>
#include<queue>
#include<set>

using namespace std;

#define rep(i,n) for(int i=0;i<n;i++)
#define reps(i,n) for(int i=1;i<=n;i++)

class S{
	public:
	char a,b,c,d;
	int val;
	S(int a,int b,int c,int d,int val):
	a(a),b(b),c(c),d(d),val(val){}
};

char ch[55][55][55][55];

int main(){
	while(1){
		int n,m;
		cin>>n>>m;
		if(n==0)break;
		
		int sa,sb,sc,sd;
		cin>>sa>>sb>>sc>>sd;
		
		int masu[55][55]={0};
		reps(i,n){
			reps(j,m){
				cin>>masu[i][j];
			}
		}
		
		rep(i,55)rep(j,55)rep(k,55)rep(p,55)ch[i][j][k][p]=0;
		
		queue<S> que;
		que.push(S(sb,sa,sd,sc,0));
		
		int dx[4]={-1,0,1,0};
		int dy[4]={0,1,0,-1};
		
		int ans=-1;
		while(1){
			if(que.empty())break;
			
			S u = que.front();
			que.pop();
			
			
			if(u.a<=0 || u.b<=0 || u.c<=0 || u.d<=0)continue;
			if(u.a>m || u.c>m || u.b>n || u.d>n)continue;
			
			if(ch[u.a][u.b][u.c][u.d]==1)continue;
			ch[u.a][u.b][u.c][u.d]=1;
			
			//printf("%d %d  %d %d  %d\n",u.a,u.b,u.c,u.d,u.val);
			
			if(masu[u.b][u.a]==1 || masu[u.d][u.c]==1)continue;
			
			if(u.a == u.c && u.b==u.d){
				ans = u.val;
				break;
			}
			
			S e = u;
			e.val++;
			rep(i,4){
				e.a += dx[i];
				e.b += dy[i];
				e.c -= dx[i];
				e.d -= dy[i];
					
				que.push(e);
				
				e.c += dx[i];
				e.d += dy[i];
				e.a -= dx[i];
				e.b -= dy[i];
			}
		}
		if(ans==-1){
			puts("NA");
		}else
		printf("%d\n",ans);
	}
}

C++: #include<cstdio>
#include<cstring>
#include<map>
#include<queue>
#include<algorithm>
using namespace std;
#define INF 4000
typedef pair<int,int> p;
int xs[] = {0, 1, 0, -1}, ys[] = {1, 0, -1, 0};
int x, y;
int field[55][55];
bool dp[55][55][55][55];

int main(){
  int tx, ty, kx, ky;
  while(true){
    scanf("%d%d", &x, &y);
    memset(dp, false, sizeof(dp));
    memset(field, -1, sizeof(field));
    if(x == 0 && y == 0) return 0;
    scanf("%d%d", &tx, &ty);
    scanf("%d%d", &kx, &ky);
    for(int i = 1;i <= y;i++){
      for(int j = 1;j <= x;j++){
	scanf("%d", &field[j][i]);
      }
    }
    int ans = 0;
    bool fin = false;
    queue<pair<p, p> > q;
    q.push(make_pair(p(tx, ty), p(kx, ky)));
    dp[tx][ty][kx][ky] = true;
    while(!q.empty() && !fin && ans < 105){
      int len = q.size();
      ans++;
      while(len-- && !fin){
	pair<p, p> tmp;
	tmp = q.front();
	q.pop();
	for(int i = 0;i < 4;i++){
	  tx = tmp.first.first + xs[i];
	  ty = tmp.first.second + ys[i];
	  kx = tmp.second.first - xs[i];
	  ky = tmp.second.second - ys[i];
	  if(field[tx][ty] != 0){
	    tx = tmp.first.first;
	    ty = tmp.first.second;
	  }
	  if(field[kx][ky] != 0){
	    kx = tmp.second.first;
	    ky = tmp.second.second;
	  }
	  if(dp[tx][ty][kx][ky])continue;
	  dp[tx][ty][kx][ky] = true;
	  q.push(make_pair(p(tx, ty), p(kx, ky)));
	  if(tx == kx && ty == ky){
	    fin = true;
	    break;
	  }
	}
      }
    }
    if(!fin || ans >= 100)
      puts("NA");
    else
      printf("%d\n", ans);
  }
}