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<queue>
using namespace std;
const int N = 50;
#define dx(y, x) field[(y) + 10][(x) + 10]
#define dy(a, b, c, d) move[(a) + 10][(b) + 10][(c) + 10][(d) + 10]
#define FOR(a, b) for (int (a) = 0; (a) < (int)(b); ++(a))

int field[N + 100][N + 100] = {false};
bool move[N + 100][N + 100][N + 100][N + 100];

class C{
    public:
        int ty, tx, ky, kx, step;
        C(int tty, int ttx, int kky, int kkx, int s);
};

C::C(int tty, int ttx, int kky, int kkx, int s){
    ty = tty;
    tx = ttx;
    ky = kky;
    kx = kkx;
    step = s;
}

int main(){

    int w, h, stx, sty, skx, sky;
    while(cin >>w >>h){
        if(w == 0 && h == 0) break;

        FOR(i, (N + 100)){
            FOR(j, (N + 100)){
                field[i][j] = -1;
            }
        }

        cin >>stx >>sty >>skx >>sky;
        --stx; --sty; --skx; --sky;

        FOR(i, h){
            FOR(j, w){
                cin >>dx(i, j);
            }
        }

        queue<C> qu;
        C cls(sty, stx, sky, skx, 0);
        qu.push(cls);
        dy(sty, stx, sky, skx) = true;

        int cnt = 0;
        bool endFlg = false;
        int mx[] = {0, 1, 0, -1};
        int my[] = {-1, 0, 1, 0};

        while(!qu.empty()){
            C now = qu.front(); qu.pop();

            if(now.step >= 100) break;
            if(now.ty == now.ky && now.tx == now.kx){
                endFlg = true;
                cout <<now.step <<endl;
                break;
            }

            FOR(i, 4){
                FOR(j, 4){
                    int nty = now.ty + my[i];
                    int ntx = now.tx + mx[i];
                    int nky = now.ky + (my[i] * -1);
                    int nkx = now.kx + (mx[i] * -1);
                    if(!dy(nty, ntx, nky, nkx) && !(dx(nty, ntx) == 1 && dx(nky, nkx) == 1) && dx(nty, ntx) != -1 && dx(nky, nkx) != -1){

                        if(dx(nty, ntx) == 1){
                            nty = now.ty; ntx = now.tx;
                        }
                        if(dx(nky, nkx) == 1){
                            nky = now.ky; nkx = now.kx;
                        }
                        if(dy(nty, ntx, nky, nkx)) continue;

                        C tmp2(nty, ntx, nky, nkx, now.step + 1);
                        qu.push(tmp2);
                        dy(nty, ntx, nky, nkx) = true;
                    }
                }
            }
        }

        if(!endFlg) cout <<"NA" <<endl;
    }
    return 0;
}

C++: #include <iostream>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <queue>
using namespace std;

struct NODE{
	int x1,y1,x2,y2,c;
	NODE(int x1,int y1,int x2,int y2,int c) : x1(x1) , y1(y1) , x2(x2) , y2(y2) , c(c) {}
	
};

bool memo[52][52][52][52];

int main(){
	int n;
	int W,H;
	while(cin >> W >> H && W){
		int sx,sy,gx,gy;
		cin >> sx >> sy >> gx >> gy;
		int t[52][52];
		for(int i = 0 ; i < 52 ; i++)
			for(int j = 0 ; j < 52 ; j++)
				t[i][j] = 1;
			
		for(int i = 1 ; i <= H ; i++)
			for(int j = 1 ; j <= W ; j++)
				cin >> t[i][j];
		queue<NODE> Q;
		Q.push(NODE(sx,sy,gx,gy,0));
		memset(memo,0,sizeof(memo));
		int dx[] = {-1,0,1,0};
		int dy[] = {0,1,0,-1};
		while(Q.size()){
			NODE q = Q.front(); Q.pop();
			if( q.c > 100 ) break;
			if( q.x1 == q.x2 && q.y1 == q.y2 ) {
				cout << q.c << endl;
				goto exit;
			}
			if( memo[q.x1][q.y1][q.x2][q.y2] ) continue;
			else memo[q.x1][q.y1][q.x2][q.y2] = true;
			for(int i = 0 ; i < 4 ; i++){
				int x1 = q.x1 + dx[i] , y1 = q.y1 + dy[i];
				int x2 = q.x2 - dx[i] , y2 = q.y2 - dy[i];
				if( t[y1][x1] ) x1 = q.x1 , y1 = q.y1;
				if( t[y2][x2] ) x2 = q.x2 , y2 = q.y2;
				Q.push(NODE(x1,y1,x2,y2,q.c+1));
			}
		}
		cout << "NA" << endl;
		exit:;
		
	}
}

C++: #include <iostream>
#include <vector>
#include <utility>
#include <queue>
#include <set>
using namespace std;

const int needleX[4] = {-1, 0, 1, 0};
const int needleY[4] = {0, -1, 0, 1};

pair<int, int> newPoint(pair<int, int> nowPoint, int i, vector<vector<bool> >& depart, bool takayuki){
  pair<int, int> result;
  result.first = nowPoint.first + (needleX[i] * (takayuki ? 1 : -1));
  result.second = nowPoint.second + (needleY[i] * (takayuki ? 1 : -1));
  if(!depart[result.first][result.second]){ result = nowPoint; }
  return result;
}

int main(void){
  while(true){
    int w, h;
    cin >> w >> h;
    if(w == 0 && h == 0){ break; }
    pair<int, int> takayuki, kazuyuki;
    cin >> takayuki.first >> takayuki.second;
    cin >> kazuyuki.first >> kazuyuki.second;

    int input;
    vector<vector<bool> > depart(w + 2, vector<bool>(h + 2, false));
    for(int i = 1; i <= w; i++){
      for(int j = 1; j <= h; j++){
        cin >> input;
        if(input == 0){ depart[i][j] = true; }
      }
    }

    int ans = -1;
    set<pair<pair<int, int>, pair<int, int> > > used;
    queue<pair<int, pair<pair<int, int>, pair<int, int> > > > wait;
    used.insert(make_pair(takayuki, kazuyuki));
    wait.push(make_pair(0, make_pair(takayuki, kazuyuki)));
    while(!wait.empty()){
      int cost = wait.front().first;
      pair<int, int> t = wait.front().second.first;
      pair<int, int> k = wait.front().second.second;
      wait.pop();
      
      if(t == k){
        ans = cost;
        break;
      }

      for(int i = 0; i < 4; i++){
        pair<int, int> newt = newPoint(t, i, depart, true);
        pair<int, int> newk = newPoint(k, i, depart, false);
        if(used.count(make_pair(newt, newk)) == 0){
          used.insert(make_pair(newt, newk));
          wait.push(make_pair(cost + 1, make_pair(newt, newk)));
        }
      }
    }
    
    if(ans == -1){ cout << "NA" << endl; }
    else{ cout << ans << endl; }
  }
  
  return 0;
}