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 now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}

		if _, ok := memo[now.Person]; ok {
			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++
			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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
using namespace std;
static const double EPS = 1e-5;
typedef long long ll;
typedef pair<int,int> pi;
#define rep(i,n) for(int i=0;i<n;i++)
#define mp make_pair


int dx[]={0,-1,0,1};
int dy[]={-1,0,1,0};
bool v[50][50][50][50];
int f[50][50];
int x,y;
int tx,ty,kx,ky;


main(){
	while(cin>>x>>y,x){
		cin>>tx>>ty>>kx>>ky;
		--tx;--ty;--kx;--ky;
		rep(i,x)rep(j,y)cin>>f[i][j];
		memset(v,0,sizeof(v));

		v[tx][ty][kx][ky]=1;
		queue<pair<pair<pi,pi>,int> > Q;
		Q.push(mp(mp(mp(tx,ty),mp(kx,ky)),0));
		
		while(!Q.empty()){
			tx=Q.front().first.first.first;
			ty=Q.front().first.first.second;
			kx=Q.front().first.second.first;
			ky=Q.front().first.second.second;
			int time=Q.front().second;Q.pop();
			
			
			rep(d,4){
				int ntx=tx+dx[d],nty=ty+dy[d];
				int nkx=kx-dx[d],nky=ky-dy[d];
				
				if(ntx<0 || ntx>=x || nty<0 || nty>=y || f[ntx][nty])ntx=tx,nty=ty;
				if(nkx<0 || nkx>=x || nky<0 || nky>=y || f[nkx][nky])nkx=kx,nky=ky;
				if(v[ntx][nty][nkx][nky] || time>=99)continue;
				if(ntx==nkx && nty==nky){
					cout<<time+1<<endl;
					goto END;
				}
				
				Q.push(mp(mp(mp(ntx,nty),mp(nkx,nky)),time+1));
				v[ntx][nty][nkx][nky]=1;
			}
		}
		
		puts("NA");END:;
	}
}

C++: #include <iostream>
#include <algorithm>
#include <queue>
#include <cstring>

using namespace std;

typedef pair<int, int> Pii;
typedef pair<int, pair<Pii, Pii> > Tpl;
#define fi first
#define se second
int W, H;
int const INF = 1<<29;
inline bool inF(int x, int y) {
  return 0<=x&&x<W&&0<=y&&y<H;
}

int main() {

  int const dx[] = {-1,0,1,0};
  int const dy[] = {0,-1,0,1};
  while(cin >> W >> H && (W|H)) {
    int tx, ty, kx, ky; cin >> tx >> ty >> kx >> ky;
    int grid[51][51];
    for(int i=0; i<H; i++)
      for(int j=0; j<W; j++)
	cin >> grid[i][j];
    
    static int vis[51][51][51][51];
    fill(vis[0][0][0], vis[0][0][0]+H*W*H*W, INF);
    
    queue<Tpl> Q;
    Q.push(Tpl(make_pair(0, make_pair(Pii(tx, ty), Pii(kx, ky)))));
    vis[ty][tx][ky][kx] = 0;
    int ans = -1;
    while(!Q.empty()) {
      Tpl t = Q.front(); Q.pop();
      const int tx = t.se.fi.fi, ty = t.se.fi.se, kx = t.se.se.fi, ky = t.se.se.se;
      const int cost = t.fi;
      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(!inF(ntx, nty) && !inF(nkx, nky)) continue;
	if(!inF(ntx, nty)) ntx = tx, nty = ty;
	if(!inF(nkx, nky)) nkx = kx, nky = ky;
	if(grid[nty][ntx] && grid[nky][nkx]) continue;
	if(grid[nty][ntx]) ntx = tx, nty = ty;
	if(grid[nky][nkx]) nkx = kx, nky = ky;
	if(vis[nty][ntx][nky][nkx] > cost+1) {
	  vis[nty][ntx][nky][nkx] = cost+1;
	  if(ntx == nkx && nty == nky) { ans = cost+1; goto EXIT; }
	  Q.push(Tpl(cost+1, make_pair(Pii(ntx, nty), Pii(nkx, nky))));
	}
      }
    }
    
  EXIT:;
    if(ans == -1) cout << "NA" << endl;
    else cout << ans << endl;
  }
  
  return 0;
}

C++: #include<cstdio>
#include<iostream>
#include<queue>
#include<string.h>
#include<cstring>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[52][52][52][52];
int main(){
	PP S;
	queue<PP> P;
	int  w,h;
	int d=0,i=0,j=0,l=-1,D[52][52];
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&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;
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			printf("%d\n",S.Z);
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.ty][S.tx][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-kx[l];
		S.ky=S.ky-ky[l];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	d=0;
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}