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 <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <string>
#include <cmath>
#include <queue>
#include <map>
using namespace std;

#define REP(i,n) for(int i=0;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()
const int INF = 1<<29;

typedef pair<int,int> pii;
typedef pair<pii, pii> piiii;

int X, Y;
int ba[50][50];

int dtx[] = {0,1,0,-1};
int dty[] = {-1,0,1,0};
int dkx[] = {0,-1,0,1};
int dky[] = {1,0,-1,0};

map<piiii, bool> visited;

int solve(pii T, pii K) {
  queue<pair<piiii, int> > Q;
  Q.push(make_pair(piiii(T,K), 0));
  while(Q.size()) {
    pii tt = Q.front().first.first, kk = Q.front().first.second;
    int m = Q.front().second;
    Q.pop();
    if (m >= 100) break;
    if (tt == kk) return m;
    visited[piiii(tt,kk)] = true;
//    cout << tt.first << ","<<tt.second<<" " << kk.first<<","<<kk.second << endl;
    REP(k,4) {
      int txx = tt.first + dtx[k];
      int tyy = tt.second + dty[k];
      int kxx = kk.first + dkx[k];
      int kyy = kk.second + dky[k];

      if (txx < 0 || X <= txx || tyy < 0 || Y <= tyy || ba[txx][tyy]) {
        txx -= dtx[k];
        tyy -= dty[k];
      }
      if (kxx < 0 || X <= kxx || kyy < 0 || Y <= kyy || ba[kxx][kyy]) {
        kxx -= dkx[k];
        kyy -= dky[k];
      }
      if (!visited[piiii(pii(txx, tyy),pii(kxx, kyy))])
        Q.push(make_pair(piiii(pii(txx, tyy), pii(kxx, kyy)), m+1));
    }
  }
  return -1;
}

int main() {
  while(cin >> X >> Y, X||Y) {
    int tx, ty, kx, ky;
    cin >> tx >> ty;
    cin >> kx >> ky;
    tx--;ty--;kx--;ky--;
    REP(y,Y)
      REP(x,X)
        cin >> ba[x][y];
    int res = solve(pii(tx,ty), pii(kx,ky));
    if (res < 0)
      cout << "NA" << endl;
    else
      cout << res << endl;
  }
}

C++: #include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<queue>
#include<iostream>
using namespace std;
struct data{
    int x;
    int y;
    int u;
    int v;
    int t;
};

bool vis[60][60][60][60] = {};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
int main(void){
    int w,h;
    while(cin>>w>>h,w){
        int x,y,u,v;
        cin>>x>>y>>u>>v;
        bool screen[60][60] = {};
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin>>screen[i][j];
            }
        }
        data D;
        D.x = x,D.y = y;
        D.u = u,D.v = v;
        D.t = 0;
        queue<data> Q;
        Q.push(D);

        while(!Q.empty()){
            data E = Q.front();Q.pop();

            vis[E.x][E.y][E.u][E.v] = true;
            vis[E.u][E.v][E.x][E.y] = true;
            if(E.x == E.u&&E.y == E.v){
                cout<<E.t<<endl;
                goto e;
            }
            if(E.t>99)break;
            for(int i = 0;i < 4;i++){

                    data F = E;
                    F.t++;
                    F.x+=dx[i],F.y+=dy[i],F.u+=dx[(i+2)%4],F.v+=dy[(i+2)%4];
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h)){
                        F.x = E.x,F.y = E.y;
                    }
                    else if(screen[F.x][F.y])F.x = E.x,F.y = E.y;
                    if(!(0<=F.u&&F.u<w&&0<=F.v&&F.v<h)){
                        F.u = E.u,F.v = E.v;
                    }
                    else if(screen[F.u][F.v])F.u = E.u,F.v = E.v;
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h&&0<=F.u&&F.u<w&&0<=F.v&&F.v<h))continue;
                    if(!vis[F.x][F.y][F.u][F.v]&&!vis[F.u][F.v][F.x][F.y]){
                        Q.push(F);
                    }

            }

        }
        cout<<"NA"<<endl;
        e:;
    }


    return 0;
}

C++: #include <iostream>
#include <queue>
#include <map>
using namespace std;
int main(){
	int x,y;
	int tx,ty,kx,ky;
	int Tx,Ty,Kx,Ky;
	int Px[4]={0,1,0,-1},Py[4]={1,0,-1,0};
	int Qx[4]={0,-1,0,1},Qy[4]={-1,0,1,0};
	int date[55][55];
	int beta;
	while(cin>>x>>y,x){
		cin>>tx>>ty>>kx>>ky;
		for(int i=1;i<=y;i++)for(int j=1;j<=x;j++)cin>>date[j][i];
		for(int i=1;i<=x;i++)date[i][0]=date[i][y+1]=1;
		for(int i=1;i<=y;i++)date[0][i]=date[x+1][i]=1;
		queue<int>name;
		map<int ,int>time;
		name.push(tx*1000000+ty*10000+kx*100+ky);
		time[tx*1000000+ty*10000+kx*100+ky]=0;
		beta=tx*1000000+ty*10000+kx*100+ky;
		int flag=1;
		while(name.empty()==0){
			if(name.front()/10000==name.front()%10000&&time[name.front()]<100){
				cout<<time[name.front()]<<endl;
				flag=0;
				break;
			}
			else if(time[name.front()]<100){
				tx=name.front()/1000000%100;
				ty=name.front()/10000%100;
				kx=name.front()/100%100;
				ky=name.front()/1%100;
				
				for(int i=0;i<4;i++){
					Tx=tx+Px[i];
					Ty=ty+Py[i];
					Kx=kx+Qx[i];
					Ky=ky+Qy[i];
					if(date[Tx][Ty]){
						Tx=tx;
						Ty=ty;
					}
					if(date[Kx][Ky]){
						Kx=kx;
						Ky=ky;
					}
					if(time[Tx*1000000+Ty*10000+Kx*100+Ky]==0&&beta!=Tx*1000000+Ty*10000+Kx*100+Ky){
						time[Tx*1000000+Ty*10000+Kx*100+Ky]=time[name.front()]+1;
						name.push(Tx*1000000+Ty*10000+Kx*100+Ky);
					}
				}
			}
			name.pop();
		}
		if(flag)cout<<"NA"<<endl;
	}
	return 0;
}