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 <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <cstring>
#include <cstdlib>

using namespace std;

char field[51][51];

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

int w,h;
int bfs(int stx,int sty,int skx,int sky){

	queue<pair<pair<int,int>,pair<int,int> > > *prv=new queue<pair<pair<int,int>,pair<int,int> > >();
	queue<pair<pair<int,int>,pair<int,int> > > *nxt=new queue<pair<pair<int,int>,pair<int,int> > >();
	prv->push(make_pair(make_pair(sty,stx),make_pair(sky,skx)));
	int cnt=1;
	bool passed[51][51][51][51];
	memset(passed,0,sizeof(passed));
	while(prv->size()){
		if(cnt>100)
			return -1;
		while(prv->size()){
			pair<pair<int,int>,pair<int,int> > ppp = prv->front();
			prv->pop();
			pair<int,int> tp=ppp.first;
			pair<int,int> kp=ppp.second;
			if(passed[tp.first][tp.second][kp.first][kp.second]){
				continue;
			}
			passed[tp.first][tp.second][kp.first][kp.second]=true;
			for(int i = 0; i < 4; i++){
				int nky=kp.first+dy[i];
				int nkx=kp.second+dx[i];
				int nty=tp.first-dy[i];
				int ntx=tp.second-dx[i];
				// ©¸ä«ªÍÍOÉoÈ¢ê
				if(nky>=0&&nkx>=0&&nkx<w&&nky<h&&field[nky][nkx]=='0'){
					// ½©ä«ªÍÍOÉoéê
					if(!(nty>=0&&ntx>=0&&ntx<w&&nty<h&&field[nty][ntx]=='0')){
						nxt->push(make_pair(tp,make_pair(nky,nkx)));
						if(tp==make_pair(nky,nkx))
							return cnt;
					}
					else{
						nxt->push(make_pair(make_pair(nty,ntx),make_pair(nky,nkx)));
						if(make_pair(nty,ntx)==make_pair(nky,nkx))
							return cnt;
					}
				}
				// ½©ä«ªÍÍOÉoÈ¢ê
				else if(nty>=0&&ntx>=0&&ntx<w&&nty<h&&field[nty][ntx]=='0'){
					// ©¸ä«ªÍÍOÉoéê
					if(!(nky>=0&&nkx>=0&&nkx<w&&nky<h&&field[nky][nkx]=='0')){
						nxt->push(make_pair(make_pair(nty,ntx),kp));
						if(kp==make_pair(nty,ntx))
							return cnt;
					}
					else{
						nxt->push(make_pair(make_pair(nty,ntx),make_pair(nky,nkx)));
						if(make_pair(nty,ntx)==make_pair(nky,nkx))
							return cnt;
					}
				}
			}
		}
		cnt++;
		swap(prv,nxt);
	}
	return -1;
}

int main(){

	while(cin>>w>>h&&!(w==0&&h==0)){
		int ty,tx,kx,ky;
		cin>>tx>>ty>>kx>>ky;
		ty--;
		tx--;
		kx--;
		ky--;
		for(int i = 0; i < h; i++){
			for(int j= 0; j < w; j++){
				cin>>field[i][j];
			}
		}

		int ret=bfs(tx,ty,kx,ky);
		if(ret==-1)
			cout<<"NA"<<endl;
		else
			cout<<ret<<endl;
	}

	return 0;
}

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;
const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-9;

int W, H;
pii tp, kp;
int maps[50][50];
map<ppp, int> dp;

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]);
		
		dp.clear();
		
		queue<ppp> que;
		que.push(ppp(tp, kp));
		dp[ppp(tp, kp)] = 0;
		int ans = INF;
		
		while (!que.empty()) {
			pii p1 = que.front().fi, p2 = que.front().se;
			que.pop();
			int c = dp[ppp(p1, p2)];
			
			if (p1 == p2) { chmin(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;
				ppp next(o1 ? np1 : p1, o2 ? np2 : p2);
				if (dp.find(next) != dp.end()) continue;
				dp[next] = c + 1;
				que.push(next);
			}
		}
		
		if (ans == INF) puts("NA");
		else cout << ans << endl;
		
	}
	return 0;
}