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 ans <= now.Turn {
			continue
		}
		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<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<bitset>
#include<numeric>
using namespace std;
const int dx[]={1,0,-1,0};
const int dy[]={0,1,0,-1};
#define INF 1e+8
#define EPS 1e-7
#define PB push_back
#define fi first
#define se second
#define ll long long
#define reps(i,j,k) for(int i = (j); i < (k); i++)
#define rep(i,j) reps(i,0,j)
typedef pair<int,int> Pii;
typedef vector<int> vi;
class data{
    public:
    int ay;
    int ax;
    int by;
    int bx;
    int cnt;
    data(){}
    data(int _ay,int _ax,int _by,int _bx,int _cnt){
        ay = _ay;
        ax = _ax;
        by = _by;
        bx = _bx;
        cnt = _cnt;
    }
};
bool memo[52][52][52][52];
int main(){
    int W,H;
    while(scanf("%d%d",&W,&H),W){
        memset(memo,0,sizeof(memo));
        int ax,ay;
        int bx,by;
        int stage[52][52];
        scanf("%d%d",&ax,&ay);
        scanf("%d%d",&bx,&by);
        ax--;ay--;bx--;by--;
        rep(i,H){
            rep(j,W){
                scanf("%d",&stage[i][j]);
            }
        }
        queue < data > Q;
        Q.push(data(ay,ax,by,bx,0));
        memo[ay][ax][by][bx] = 1;
        int ans = -1;
        while(!Q.empty()){
            data d = Q.front();Q.pop();
            if(d.cnt > 100){
                break;
            }
            if(d.ax == d.bx && d.ay == d.by){
                ans = d.cnt;
                break;
            }
            rep(i,4){
                int nay,nax;
                int nby,nbx;
                nax = d.ax+dx[i];
                nay = d.ay+dy[i];
                nbx = d.bx+dx[(i+2)%4];
                nby = d.by+dy[(i+2)%4];
                if(nax < 0 || nax > W-1 || nay < 0 || nay > H-1)continue;
                if(nbx < 0 || nbx > W-1 || nby < 0 || nby > H-1)continue;
                if(stage[nay][nax] || stage[nby][nbx])continue;
                if(memo[nay][nax][nby][nbx])continue;
                memo[nay][nax][nby][nbx]  = 1;
                Q.push(data(nay,nax,nby,nbx,d.cnt+1));
                //printf("%d %d %d %d\n",nax,nay,nbx,nby);
            }
        }
        if(ans == -1)puts("NA");
        else printf("%d\n",ans);
    }
    return 0;
}

C++: #include <iostream>
#include <cstring>
#include <queue>
#include <map>
#define fr first
#define sc second
using namespace std;

typedef pair<int, int> iP;
typedef pair<iP, iP> iiP;
typedef pair<iiP, int> iiiP;

int w, h;
iP ts, ks;
int mas[51][51], used[51][51][51][51];
int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

int bfs(){
  
  memset(used, -1, sizeof(used));
  queue <iiiP> que;
  que.push(iiiP(iiP(ts, ks), 0)); used[ts.fr][ts.sc][ks.fr][ks.sc] = 0;
  while(!que.empty()){
    iiiP p = que.front(); que.pop();
    if(p.fr.fr == p.fr.sc){
      if(p.sc >= 100) return -1;
      else return p.sc;
    }
    int tx = p.fr.fr.fr, ty = p.fr.fr.sc, kx = p.fr.sc.fr, ky = p.fr.sc.sc;
    for(int i = 0; i < 4; i++){
      int ntx = tx + dx[i], nty = ty + dy[i];
      int nkx = kx - dx[i], nky = ky - dy[i];
      if(ntx >= 0 && ntx < w && nty >= 0 && nty < h && nkx >= 0 && nkx < w && nky >= 0 && nky < h && 
	 used[ntx][nty][nkx][nky] < used[tx][ty][kx][ky] + 1){
	que.push(iiiP(iiP(iP(ntx, nty), iP(nkx, nky)), p.sc + 1));
	used[ntx][nty][nkx][nky] = used[tx][ty][kx][ky] + 1;
      }
    }
  }
  return -1;

}  

int main(){
  
  while(cin >> w >> h, w||h){
    cin >> ts.fr >> ts.sc;
    cin >> ks.fr >> ks.sc;
    for(int i = 0; i < h; i++){
      for(int j = 0; j < w; j++) cin >> mas[i][j];
    }

    int ans = bfs();
    if(ans == -1) cout << "NA" << endl;
    else cout << ans << endl;
  }

}