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<bits/stdc++.h>
#define P pair<int,int>
using namespace std;

bool c[52][52];
int d[52][52];
int x[4] = { -1,0,0,1 }, y[4] = { 0,-1,1,0 };
int main() {
	int a, b;
	while (cin >> a >> b, a | b) {
		memset(c, true, sizeof(c));
		memset(d,-1,sizeof(d));
		int e, f, g, h; cin >> e >> f >> g >> h;
		for (int i = 0; i < b; i++) {
			for (int j = 0; j < a; j++) {
				cin >> c[j + 1][i + 1];
			}
		}
		if (((e + g) & 1) == ((f + h) & 1)) {
		queue<P>Q;
		Q.push(P(e,f));
		d[e][f] = 0;
		while (Q.size()) {
			P o = Q.front(); Q.pop();
			for (int i = 0; i < 4; i++) {
				if (!c[o.first + x[i]][o.second + y[i]]&&!c[e+g-(o.first + x[i])][f+h-(o.second + y[i])]&& d[o.first + x[i]][o.second + y[i]] ==-1) {
					d[o.first + x[i]][o.second + y[i]] = d[o.first][o.second] + 1;
					Q.push(P(o.first + x[i], o.second + y[i]));
				}
			}
		}
		if (d[(e + g) / 2][(f + h) / 2] == -1)puts("NA");
		else cout << d[(e + g) / 2][(f + h) / 2] << endl;
		}
		else puts("NA");
	}
}

C++: #include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <string>
#include <algorithm>
#include <utility>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <queue>
#include <map>
#include <set>
#define INF (2000000000)
#define MOD (1000000007)
using namespace std;

typedef vector<int> VI;
typedef vector<int>::iterator VII;
typedef vector<double> VD;
typedef vector<double>::iterator VDI;
typedef pair<int, int> P;


typedef struct
{
	int tx, ty, kx, ky;
} POS;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};

int maze[100][100];
int X, Y;
POS f;
int d[52][52][52][52];

int search()
{
	queue<POS> que;
	
	for (int i = 0; i < 52; i++){
		for (int j = 0; j < 52; j++){
			for (int k = 0; k < 52; k++){
				for (int l = 0; l < 52; l++){
					d[i][j][k][l] = INF;
				}
			}
		}
	}
	
	que.push(f);
	d[f.tx][f.ty][f.kx][f.ky] = 0;
	
	while (que.size()){
		POS now = que.front();
		que.pop();
		
		//printf("%d %d %d %d\n", now.tx, now.ty, now.kx, now.ky);
		
		if (now.tx == now.kx && now.ty == now.ky){
			return (d[now.tx][now.ty][now.kx][now.ky]);
		}
		
		for (int i = 0; i < 4; i++){
			POS to;
			//if (maze[now.tx + dx[i]][now.ty + dy[i]] && maze[now.kx - dx[i]][now.ky - dy[i]]){
			//	continue;
			//}
			
			if (maze[now.tx + dx[i]][now.ty + dy[i]]){
				to.tx = now.tx;
				to.ty = now.ty;
			}
			else {
				to.tx = now.tx + dx[i];
				to.ty = now.ty + dy[i];
			}
			
			if (maze[now.kx - dx[i]][now.ky - dy[i]]){
				to.kx = now.kx;
				to.ky = now.ky;
			}
			else {
				to.kx = now.kx - dx[i];
				to.ky = now.ky - dy[i];
			}
			
			//to.tx = now.tx + dx[i];
			//to.ty = now.ty + dy[i];
			//to.kx = now.kx - dx[i];
			//to.ky = now.ky - dy[i];
			
			//printf("%d %d %d %d\n", to.tx, to.ty, to.kx, to.ky);
			
			if (d[to.tx][to.ty][to.kx][to.ky] == INF && d[now.tx][now.ty][now.kx][now.ky] < 99){
				que.push(to);
				d[to.tx][to.ty][to.kx][to.ky] = d[now.tx][now.ty][now.kx][now.ky] + 1;
			}
		}
	}
	
	return (-1);
}

int main()
{
	while (scanf("%d %d", &X, &Y), X + Y){
		scanf("%d %d", &f.tx, &f.ty);
		scanf("%d %d", &f.kx, &f.ky);
		
		for (int i = 0; i < 100; i++){
			for (int j = 0; j < 100; j++){
				maze[i][j] = 1;
			}
		}
		
		for (int i = 1; i <= Y; i++){
			for (int j = 1; j <= X; j++){
				scanf("%d", &maze[j][i]);
			}
		}
		
		//for (int i = 0; i <= Y + 1; i++){
		//	for (int j = 0; j <= X + 1; j++){
		//		printf("%d ", maze[j][i]);
		//	}
		//	puts("");
		//}
		
		int r = search();
		if (r != -1) printf("%d\n", r);
		else puts("NA");
	}
	
	return 0;
}

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

int  f[50][50];
bool v[50][50][50][50];

int dx[] = {0,0,1,-1};
int dy[] = {1,-1,0.0};

int main()
{
	int X,Y,tx,ty,kx,ky;
	while(cin >> X >> Y, X||Y)
	{
		cin >> tx >> ty >> kx >> ky;

		for(int y=0; y<Y; y++)
		for(int x=0; x<X; x++)
			cin >> f[y][x];

		queue<int> q;
		memset(v,0,sizeof(v));
		q.push(tx-1); q.push(ty-1);
		q.push(kx-1); q.push(ky-1);

		int  turn = 0;
		bool flag = false;

		while(!q.empty())
		{
			int n=q.size()/4;
			for(int k=0; k<n; k++)
			{
				tx = q.front(); q.pop();
				ty = q.front(); q.pop();
				kx = q.front(); q.pop();
				ky = q.front(); q.pop();

				if(tx==kx && ty&&ky)
				{
					flag=true;
					break;
				}

				v[tx][ty][kx][ky] = 1;

				for(int d=0; d<4; d++)
				{
					int ntx = tx+dx[d];
					int nty = ty+dy[d];
					int nkx = kx-dx[d];
					int nky = ky-dy[d];

					if(ntx<1 || X<ntx || nty<1 || Y<nty || f[nty][ntx])
					{
						ntx = tx;
						nty = ty;
					}
					if(nkx<1 || X<nkx || nky<1 || Y<nky || f[nky][nkx])
					{
						nkx = kx;
						nky = ky;
					}

					if(!v[ntx][nty][nkx][nky])
					{
						q.push(ntx); q.push(nty); q.push(nkx); q.push(nky);
					}
				}
			}

			if(flag) break;
			if(turn++>=100) break;
		}

		if(flag)
		{
			cout << turn << endl;
		}
		else
		{
			cout << "NA" << endl;
		}
	}
}