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 <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()
#define INF 1<<30

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<P,P> PP;
typedef pair<PP,int> PPi;

int grid[105][105];
bool vis[50][50][50][50];

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

struct POS{
	int tx, ty, kx, ky, t;
	POS (int _tx, int _ty, int _kx, int _ky, int _t ) : tx(_tx), ty(_ty), kx(_kx), ky(_ky), t(_t) {}
	bool operator>(const POS &a ) const{ return t > a.t; }
};

int main()
{
//	cut here before submit 
//	freopen ("testcase.stray_twins", "r", stdin );
	int w, h;
	while (scanf ("%d %d", &w, &h ), w, h ){
		memset (grid, 0, sizeof (grid ) );
		memset (vis, false, sizeof (vis ) );
			
		int tx, ty;
		scanf ("%d %d", &tx, &ty );
		tx--, ty--;
		int kx, ky;
		scanf ("%d %d", &kx, &ky );
		kx--, ky--;
		rep (i, h ){
			rep (j, w ){
				scanf (" %d", &grid[i][j] );
			} // end rep
		} // end rep

		vis[tx][ty][kx][ky] = true;
		priority_queue<POS, vector<POS>, greater<POS> > que;
		POS first (tx, ty, kx, ky, 0 );
		que.push (first );
		int res = INF;
		while (!que.empty() ){
			POS curr = que.top(); que.pop();
			int ctx = curr.tx;
			int cty = curr.ty;
			int ckx = curr.kx;
			int cky = curr.ky; 
			int ct  = curr.t;
			if (ctx == ckx && cty == cky && ct < 100 ){
				res = ct;
				break;
			} // end if

			rep (k, 4 ){
				int ntx = ctx + dx[k], nty = cty + dy[k];
				int nkx = ckx - dx[k], nky = cky - dy[k];
				if (ntx < 0 || ntx >= w || nty < 0 || nty >= h || grid[nty][ntx] == 1 ){
					ntx = tx, nty = ty;
				} // end if
				if (nkx < 0 || nkx >= w || nky < 0 || nky >= h || grid[nky][nkx] == 1 ){
					nkx = kx, nky = ky;
				} // end if
				if (vis[ntx][nty][nkx][nky] || ct + 1 >= 100 ) continue;
				vis[ntx][nty][nkx][nky] = true;
				POS next (ntx, nty, nkx, nky, ct+1 ); 
				que.push (next );
			} // end rep
		} // end while
		if (res != INF ){
			printf ("%d\n", res );
		}else{
			printf ("NA\n" );
		} // end if

	} // end loop
		
	return 0;
}

C++: #include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<cassert>
#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<utility>
#include<numeric>
#include<algorithm>
#include<bitset>
#include<complex>

using namespace std;

typedef long long Int;
typedef vector<int> vint;
typedef pair<int,int> pint;
#define mp make_pair

template<class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cout << *i << " "; cout << endl; }
template<class T> void chmin(T &t, T f) { if (t > f) t = f; }
template<class T> void chmax(T &t, T f) { if (t < f) t = f; }
int in() { int x; scanf("%d", &x); return x; }

class Pos{
public:
	int tx,ty,kx,ky,n;
	bool operator<(const Pos &pos)const{return n>pos.n;}
};

int memo[50][50][50][50];
int m[50][50];

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	while(cin>>X>>Y,X){
		memset(memo,-1,sizeof(memo));
		priority_queue<Pos> que;
		cin>>tx>>ty>>kx>>ky;
		tx--;ty--;kx--;ky--;
		int i,j;
		for(i=0;i<Y;i++){
			for(j=0;j<X;j++){
				m[i][j]=in();
			}
		}
		Pos pos;
		pos.tx=tx;
		pos.ty=ty;
		pos.kx=kx;
		pos.ky=ky;
		pos.n=0;
		que.push(pos);
		while(!que.empty()){
			pos=que.top();
			que.pop();
			if(pos.tx==pos.kx&&pos.ty==pos.ky)break;
			if(memo[pos.tx][pos.ty][pos.kx][pos.ky]>=0)continue;
			memo[pos.tx][pos.ty][pos.kx][pos.ky]=pos.n;
			int xx[]={1,-1,0,0};
			int yy[]={0,0,1,-1};
			Pos next;
			for(i=0;i<4;i++){
				if(0<=pos.tx+xx[i]&&pos.tx+xx[i]<X&&0<=pos.ty+yy[i]&&pos.ty+yy[i]<Y&&m[pos.ty+yy[i]][pos.tx+xx[i]]==0){
					next.tx=pos.tx+xx[i];
					next.ty=pos.ty+yy[i];
				}else{
					next.tx=pos.tx;
					next.ty=pos.ty;
				}
				if(0<=pos.kx-xx[i]&&pos.kx-xx[i]<X&&0<=pos.ky-yy[i]&&pos.ky-yy[i]<Y&&m[pos.ky-yy[i]][pos.kx-xx[i]]==0){
					next.kx=pos.kx-xx[i];
					next.ky=pos.ky-yy[i];
				}else{
					next.kx=pos.kx;
					next.ky=pos.ky;
				}
				next.n=pos.n+1;
				que.push(next);
			}
		}
		if(!que.empty()){
			cout<<pos.n<<endl;
		}else{
			cout<<"NA"<<endl;
		}
	}
	return 0;
}