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 := 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>
#include <utility>
#include <set>
#include <vector>
using namespace std;

int main(void) {
	int X, Y;

	while(cin >> X >> Y, X | Y) {
		pair<int,int> t, k;
		vector<vector<int> > depart;
		set<pair<pair<int,int>,pair<int,int> > > moved;
		queue<pair<pair<pair<int,int>, pair<int,int> >, int> > q;
		int ans = -1;

		cin >> t.second >> t.first; t.first--; t.second--;
		cin >> k.second >> k.first; k.first--; k.second--;

		for(int i = 0; i < Y; i++) {
			vector<int> v;
			for(int j = 0; j < X; j++) {
				int tmp;
				cin >> tmp;
				v.push_back(tmp);
			}
			depart.push_back(v);
		}

		moved.insert(make_pair(t, k));
		q.push(make_pair(make_pair(t,k), 0));

		for(int i = 0;; i++) {
			pair<pair<int,int>, pair<int, int> > p;
			pair<int, int> next_t, next_k;
			int n;

			if(q.empty()) {
				break;
			}

			p = q.front().first; n = q.front().second; q.pop();
			if(p.first == p.second) {
				ans = n;
				break;
			}
			if(n > 100)
				break;

			next_t.first = p.first.first; next_t.second = p.first.second;
			next_k.first = p.second.first; next_k.second = p.second.second;
			if(p.first.first + 1 < Y && depart[p.first.first + 1][p.first.second] == 0) {
				next_t.first = p.first.first + 1;
				next_t.second = p.first.second;
			}
			if(p.second.first - 1 >= 0 && depart[p.second.first - 1][p.second.second] == 0) {
				next_k.first = p.second.first - 1;
				next_k.second = p.second.second;
			}
			if(moved.insert(make_pair(next_t, next_k)).second) {
				q.push(make_pair(make_pair(next_t, next_k),n + 1));
			}

			next_t.first = p.first.first; next_t.second = p.first.second;
			next_k.first = p.second.first; next_k.second = p.second.second;
			if(p.first.first - 1 >= 0 && depart[p.first.first - 1][p.first.second] == 0) {
				next_t.first = p.first.first - 1;
				next_t.second = p.first.second;
			}
			if(p.second.first + 1 < Y && depart[p.second.first + 1][p.second.second] == 0) {
				next_k.first = p.second.first + 1;
				next_k.second = p.second.second;
			}
			if(moved.insert(make_pair(next_t, next_k)).second) {
				q.push(make_pair(make_pair(next_t, next_k),n + 1));
			}

			next_t.first = p.first.first; next_t.second = p.first.second;
			next_k.first = p.second.first; next_k.second = p.second.second;
			if(p.first.second + 1 < X && depart[p.first.first][p.first.second + 1] == 0) {
				next_t.first = p.first.first;
				next_t.second  = p.first.second + 1;
			}
			if(p.second.second - 1 >= 0 && depart[p.second.first][p.second.second - 1] == 0) {
				next_k.first = p.second.first;
				next_k.second  = p.second.second - 1;
			}
			if(moved.insert(make_pair(next_t, next_k)).second) {
				q.push(make_pair(make_pair(next_t, next_k),n + 1));
			}

			next_t.first = p.first.first; next_t.second = p.first.second;
			next_k.first = p.second.first; next_k.second = p.second.second;
			if(p.first.second - 1 >= 0 && depart[p.first.first][p.first.second - 1] == 0) {
				next_t.first = p.first.first;
				next_t.second  = p.first.second - 1;
			}
			if(p.second.second + 1 < X && depart[p.second.first][p.second.second + 1] == 0) {
				next_k.first = p.second.first;
				next_k.second  = p.second.second + 1;
			}
			if(moved.insert(make_pair(next_t, next_k)).second) {
				q.push(make_pair(make_pair(next_t, next_k),n + 1));
			}
		}

		if(ans != -1)
			cout << ans << endl;
		else
			cout << "NA" << endl;
	}
}

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

constexpr int MAX = 50;
using P = std::pair<int, int>;
using MyP = std::pair<P, P>;

int w, h;

bool board[MAX][MAX];
int d[MAX][MAX][MAX][MAX];//tx,ty,kx,ky
constexpr int dx[] = { -1,0,1,0 }, dy[] = { 0,-1,0,1 };

int bfs(P ts, P ks) {
	std::memset(d, -1, sizeof(d));
	std::queue<MyP> que;
	d[ts.first][ts.second][ks.first][ks.second] = 0;
	que.emplace(ts, ks);

	while (!que.empty()) {
		MyP p = que.front(); que.pop();
		P t = p.first, k = p.second;
		if (d[t.first][t.second][k.first][k.second] >= 100)
			break;
		std::cout << t.first << ' ' << t.second << std::endl;
		if (t == k)
			return d[t.first][t.second][k.first][k.second];
		int nx[2], ny[2];
		for (int i = 0; i < 4; ++i) {

			nx[0] = t.first + dx[i];
			ny[0] = t.second + dy[i];
			nx[1] = k.first - dx[i];
			ny[1] = k.second - dy[i];

			if (0 <= nx[0] && nx[0] < w &&
				0 <= ny[0] && ny[0] < h&&!board[ny[0]][nx[0]]) {
				if (0 <= nx[1] && nx[1] < w &&
					0 <= ny[1] && ny[1] < h && !board[ny[1]][nx[1]] && d[nx[0]][ny[0]][nx[1]][ny[1]] == -1) {
					d[nx[0]][ny[0]][nx[1]][ny[1]] =
						d[t.first][t.second][k.first][k.second] + 1;
					que.emplace(P(nx[0], ny[0]), P(nx[1], ny[1]));
				}
				else if (d[nx[0]][ny[0]][k.first][k.second] == -1) {
					d[nx[0]][ny[0]][k.first][k.second] =
						d[t.first][t.second][k.first][k.second] + 1;
					que.emplace(P(nx[0], ny[0]), k);
				}
			}
			else if (0 <= nx[1] && nx[1] < w &&
				0 <= ny[1] && ny[1] < h && !board[ny[1]][nx[1]] && d[t.first][t.second][nx[1]][ny[1]] == -1) {
				d[t.first][t.second][nx[1]][ny[1]] =
					d[t.first][t.second][k.first][k.second] + 1;
				que.emplace(t, P(nx[1], ny[1]));
			}
		}
	}
	return -1;
}

int main() {
	while (1) {
		std::cin >> w >> h;
		if (w + h == 0)
			break;
		P ts, ks;
		std::cin >> ts.first >> ts.second
			>> ks.first >> ks.second;
		--ts.first;
		--ts.second;
		--ks.first;
		--ks.second;
		for (int i = 0; i < h; ++i) {
			for (int j = 0; j < w; ++j)
				std::cin >> board[i][j];
		}
		int ans = bfs(ts, ks);
		if (ans == -1)
			std::cout << "NA" << std::endl;
		else
			std::cout << ans << std::endl;
	}
	return 0;
}