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 <queue>
#define rep2(x,from,to) for(int x=(from);(x)<(to);(x)++)
#define rep(x,to) rep2(x,0,to)
using namespace std;
bool mem[52][52][52][52] = {{{{}}}};
struct S{
	int a,b,c,d,t;
};
int dx[4] = {-1,0,1,0};
int dy[4] = {0,1,0,-1};
int main(){
	int x, y, tx, ty, kx, ky, k;
	while(cin >> x >> y, (x || y)) {
		int b[52][52] = {};
		cin >> tx >> ty >> kx >> ky;
		rep(i,y) {
			rep(j,x) {
				cin >> k;
				b[i+1][j+1] = 1-k;
			}
		}
		queue<S> q;
		S s = {tx,ty,kx,ky,0};
		q.push(s);
		while(!q.empty()) {
			S s = q.front();
			if(q.front().t >= 100) break;
			if(s.a==s.c&&s.b==s.d) break;
			q.pop();
			if(mem[s.a][s.b][s.c][s.d]++) continue;
			rep(i,4) {
				int na = s.a+dx[i], nb = s.b+dy[i], nc = s.c+dx[(i+2)%4], nd = s.d+dy[(i+2)%4];
				if(!b[nb][na]&&!b[nd][nc]) continue;
				if(!b[nb][na]) na = s.a, nb = s.b;
				if(!b[nd][nc]) nc = s.c, nd = s.d;
				S ns = {na, nb, nc, nd, s.t+1};
				q.push(ns);
			}
		}
		if(q.empty()) cout << "NA" << endl;
		else if(q.front().t >= 100) cout << "NA" << endl;
		else cout << q.front().t << endl;
	}
}

C++: #include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <set>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,j) FOR(i,0,j)
#define mp std::make_pair

typedef long long ll;
typedef unsigned long long ull;
typedef std::pair<int,int> P;
typedef std::pair<int,std::pair<P,P>> State;

const int INF = 1001001001;

// S N E W(南北東西)
const int dx[8] = {0, 0, 1, -1, 1, 1, -1, -1}, dy[8] = {1, -1, 0, 0, 1, -1, 1, -1};

int X, Y;
int tx, ty, kx, ky;
int map[50][50], d[50][50][50][50];

int main(){
    while(scanf("%d %d", &X, &Y), X || Y){
        scanf("%d %d %d %d", &tx, &ty, &kx, &ky);
        tx -= 1; ty -= 1; kx -= 1; ky -= 1;

        REP(i, Y){
            REP(j, X){
                scanf("%d", &map[i][j]);
            }
        }

        REP(i, Y){
            REP(j, X){
                REP(k, Y){
                    REP(l, X){
                        d[i][j][k][l] = INF;
                    }
                }
            }
        }

        std::queue<State> q;
        d[tx][ty][kx][ky] = 0;
        q.push(mp(0, mp(mp(tx, ty), mp(kx, ky))));

        int res = INF;
        while(!q.empty()){
            State s = q.front(); q.pop();
            int t = s.first, x1 = s.second.first.first, y1 = s.second.first.second,
                x2 = s.second.second.first, y2 = s.second.second.second;

            if(t >= 100){continue;}
            if(x1 == x2 && y1 == y2){res = std::min(res, t); continue;}
            if(t > d[x1][y1][x2][y2]){continue;}

            REP(i, 4){
                int nx1 = x1 + dx[i], ny1 = y1 + dy[i],
                    nx2 = x2 - dx[i], ny2 = y2 - dy[i];

                if(X <= nx1 || nx1 < 0 || Y <= ny1 || ny1 < 0 ||
                   map[ny1][nx1] == 1){
                    nx1 = x1; ny1 = y1;
                }

                if(X <= nx2 || nx2 < 0 || Y <= ny2 || ny2 < 0 ||
                   map[ny2][nx2] == 1){
                    nx2 = x2; ny2 = y2;
                }

                if(t + 1 < d[nx1][ny1][nx2][ny2]){
                    d[nx1][ny1][nx2][ny2] = t + 1;
                    q.push(mp(d[nx1][ny1][nx2][ny2], mp(mp(nx1, ny1), mp(nx2, ny2))));
                }
            }
        }

        if(res == INF){
            puts("NA");
        }else{
            printf("%d\n", res);
        }
    }
}

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(h + 2, vector<bool>(w + 2, false));
    for(int i = 1; i <= h; i++){
      for(int j = 1; j <= w; 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;
}