Go: package main

import (
	"container/heap"
	"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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

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)
	heap.Init(&pq)
	heap.Push(&pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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 += 1
			if next.Turn < 100-1 {
				heap.Push(&pq, next)
			}
		}
	}
	fmt.Println("NA")
}

func main() {
	var h, w int64
	for {
		fmt.Scan(&h, &w)
		if h == 0 && w == 0 {
			break
		}
		solve(h, w)
	}
}

C++: #include<queue>
#include<vector> 
#include<iostream>
#include<algorithm>
using namespace std;
int same[51][51][51][51];
struct maigo{
	int x[2];// ????????????[0]???????????????[1]
	int y[2];// ????????????[0]???????????????[1]
	int count;
};
int main(){
	queue<maigo> q;
	int tx, ty; int kx, ky;
	int **depart, X, Y;
	int flag = 0, a = 0;
	int c = 0;
	int f = 0;
	cin >> X >> Y;
	while (X != 0 && Y != 0){
		for (int i = 0; i < 51; i++){
			for (int l = 0; l < 51; l++){
				for (int i1 = 0; i1 < 51; i1++){
					for (int l1 = 0; l1 < 51; l1++){
						same[i][l][i1][l1] = 0;
					}
				}
			}
		}
		depart = new int*[Y + 2];
		for (int i = 0; i < Y + 2; i++){
			depart[i] = new int[X + 2];
		}
		for (int i = 0; i < Y + 2; i++){
			for (int l = 0; l < X + 2; l++){
				depart[i][l] = 3;
			}
		}
		cin >> tx >> ty;
		cin >> kx >> ky;
		for (int i = 1; i < Y + 1; i++){
			for (int l = 1; l < X + 1; l++){
				cin >> depart[i][l];
			}
		}
		maigo temp;
		temp.x[0] = tx; temp.y[0] = ty;
		temp.x[1] = kx; temp.y[1] = ky;
		temp.count = 1;
		q.push(temp);
		while (!q.empty()&&flag == 0){
			maigo t = q.front();
			maigo into;
			q.pop();
			if (t.count >= 100){
				a = 1; flag = 1;
				break;
			}
			int dx1[4] = { 1, 0, -1, 0 }; int dx2[4] = { 0, 1, 0, -1 };
			for (int i = 0; i < 4; i++){
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 &&
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0 &&
					same[t.x[0] + dx1[i]][t.y[0] + dx2[i]][t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					if (t.x[0] + dx1[i] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] + dx2[i] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);

					same[t.x[0] + dx1[i]][t.y[0] + dx2[i]][t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] = 1;

					into.count = t.count + 1;
					q.push(into);
				}
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] == 0 && //???????????? ok ???????????? no ?????´???
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] != 0 &&
					same[t.x[0] + dx1[i]][t.y[0] + dx2[i]][t.x[1]][t.y[1]] == 0){
					if (t.x[0] + dx1[i] == t.x[1] &&
						t.y[0] + dx2[i] == t.y[1]){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0] + dx1[i], into.y[0] = t.y[0] + dx2[i];
					into.x[1] = t.x[1], into.y[1] = t.y[1];

					same[t.x[0] + dx1[i]][t.y[0] + dx2[i]][t.x[1]][t.y[1]] = 1;

					into.count = t.count + 1;
					q.push(into);
				}
				if (depart[t.x[0] + dx1[i]][t.y[0] + dx2[i]] != 0 && //???????????? no??????????????? yes????????´???
					depart[t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0 &&
					same[t.x[0]][t.y[0]][t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] == 0){
					if (t.x[0] == t.x[1] + dx1[i] * (-1) &&
						t.y[0] == t.y[1] + dx2[i] * (-1)){
						cout << t.count << endl;
						flag = 1;
					}
					into.x[0] = t.x[0], into.y[0] = t.y[0];
					into.x[1] = t.x[1] + dx1[i] * (-1), into.y[1] = t.y[1] + dx2[i] * (-1);

					same[t.x[0]][t.y[0]][t.x[1] + dx1[i] * (-1)][t.y[1] + dx2[i] * (-1)] = 1;

					into.count = t.count + 1;
					q.push(into);
				}
			}
		}if (a == 1 || flag == 0) {
			cout << "NA" << endl;
		}while (!q.empty()) q.pop();
		a = 0; flag = 0;
		cin >> X >> Y;
	}
	return 0;
}