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 (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)
	//pq.Push(start)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		//now := pq.Pop().(*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 += 1
			if next.Turn < 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				pq = append(pq, next)
			}
		}
	}
	if ans == 101 {
		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 <algorithm>
#include <vector>
#include <sstream>
#include <cmath>
#include <queue>

#define INF (1 << 20)

using namespace std;

int W, H;

struct pos{
	int x1;
	int y1;
	int x2;
	int y2;
};

int DP[60][60][60][60];

int map_[60][60];

bool map(int x, int y){
	if(x < 0 || y < 0 || x >= W || y >= H){
		return false;
	}else if(map_[x][y] == 1){
		return false;
	}
	return true;
}

int main(){
	
	int dx_[4] = {1, 0, -1, 0};
	int dy_[4] = {0, 1, 0, -1};
	
	while(true){
		cin >> W >> H;
		if(W == 0 && H == 0){
			break;
		}
		
		int tx, ty, kx, ky;
		cin >> tx >> ty >> kx >> ky;
		tx--;
		ty--;
		kx--;
		ky--;
		for(int i = 0; i < H; i++){
			for(int j = 0; j < W; j++){
				cin >> map_[j][i];
			}
		}
		
		for(int i = 0; i <= 50; i++){
			for(int j = 0; j <= 50; j++){
				for(int k = 0; k <= 50; k++){
					for(int l = 0; l <= 50; l++){
						DP[i][j][k][l] = INF;
					}
				}
			}
		}
		
		queue<pos> que;
		pos pos_first;
		pos_first.x1 = tx;
		pos_first.y1 = ty;
		pos_first.x2 = kx;
		pos_first.y2 = ky;
		que.push(pos_first);
		
		DP[tx][ty][kx][ky] = 0;
		
		for(int step = 1; step <= 100; step++){
			
			if(que.empty()){
				break;
			}
			
			//cout << que.size() << endl;
			
			queue<pos> que_copy;
			
			while(true){
				
				if(que.empty()){
					break;
				}
				
				pos p = que.front();
				que.pop();
				for(int i = 0; i < 4; i++){
					int dx1 = dx_[i];
					int dy1 = dy_[i];
					int dx2 = -dx1;
					int dy2 = -dy1;
					if(!map(p.x1 + dx1, p.y1 + dy1)){
						dx1 = 0;
						dy1 = 0;
					}
					if(!map(p.x2 + dx2, p.y2 + dy2)){
						dx2 = 0;
						dy2 = 0;
					}
					pos pp;
					pp.x1 = p.x1 + dx1;
					pp.y1 = p.y1 + dy1;
					pp.x2 = p.x2 + dx2;
					pp.y2 = p.y2 + dy2;
					//cout << pp.x1 << " " << pp.y1 << " " << pp.x2 << " " << pp.y2 << " " << step << endl;
					if(DP[pp.x1][pp.y1][pp.x2][pp.y2] != INF){
						continue;
					}
					DP[pp.x1][pp.y1][pp.x2][pp.y2] = step;
					que_copy.push(pp);
				}
				
			}
			
			que = que_copy;
			
		}
		
		int ans = INF;
		
		for(int i = 0; i < W; i++){
			for(int j = 0; j < H; j++){
				if(DP[i][j][i][j] < ans){
					ans = DP[i][j][i][j];
				}
			}
		}
		
		if(ans == INF){
			cout << "NA" << endl;
		}else{
			cout << ans << endl;
		}
		
	}
	
	return 0;
}

C++: #include<iostream>
#include<utility>
#include<queue>
using namespace std;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
int main() {
	int W, H, tx, ty, kx, ky;
	int d[52][52];
	bool memo[52][52][52][52];
	while (true) {
		cin >> W >> H;
		if (W == 0)break;
		for (int i = 0; i < W+2; i++) {
			for (int j = 0; j < H+2; j++) {
				for (int k = 0; k < W+2; k++) {
					for (int l = 0; l < H+2; l++) {
						memo[i][j][k][l] = false;
					}
				}
			}
		}
		for (int i = 0; i < W+2; i++) {
			for (int j = 0; j < H+2; j++) {
				d[i][j] = 1;
			}
		}
		cin >> tx >> ty >> kx >> ky;
		for (int i = 1; i < H + 1; i++) {
			for (int j = 1; j < W + 1; j++) {
				cin >> d[j][i];
			}
		}
		pair<pair<int, int>, pair<int, int> >num;
		num.first.first = tx;
		num.first.second = ty;
		num.second.first = kx;
		num.second.second = ky;
		queue<pair<pair<int, int>, pair<int, int> > > q;
		q.push(num);
		int qsize = 1;
		int loopcount = 0;
		while (!q.empty()) {
			num = q.front();
			q.pop();
			if (qsize == 0) {
				qsize = q.size();
				loopcount++;
				if (loopcount == 100 || q.size()==0) {
					cout << "NA" << endl;
					break;
				}
			}
			qsize--;
			if (memo[num.first.first][num.first.second][num.second.first][num.second.second]) {
				continue;
			}
			else {
				memo[num.first.first][num.first.second][num.second.first][num.second.second] = true;
			}
			if (num.first.first == num.second.first && num.first.second == num.second.second) {
				cout << loopcount << endl;
				break;
			}
			for (int i = 0; i < 4; i++) {
				pair<pair<int, int>, pair<int, int> >copy;
				copy = num;
				copy.first.first += dx[i];
				copy.first.second += dy[i];
				if (d[copy.first.first][copy.first.second]) {
					copy.first.first -= dx[i];
					copy.first.second -= dy[i];
				}
				copy.second.first -=dx[i];
				copy.second.second -= dy[i];
				if (d[copy.second.first][copy.second.second]) {
					copy.second.first += dx[i];
					copy.second.second += dy[i];
				}
				q.push(copy);
			}
		}
	}
	return 0;
}