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 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<utility>
#include<queue>
#include<map>
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;
	bool d[52][52];
	map<pair<pair<int, int>, pair<int, int> >,bool> m;
	pair<pair<int, int>, pair<int, int> >num;
	pair<pair<int, int>, pair<int, int> >copy;
	while (true) {
		cin >> W >> H;
		if (W == 0)break;
		for (int i = 0; i < H+2; i++) {
			for (int j = 0; j < W+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];
			}
		}
		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;
		bool flg = true;
		q.push(num);
		int qsize = q.size();
		int loopcount = 0;
		while (!q.empty()) {
			num = q.front();
			q.pop();
			if (qsize == 0) {
				qsize = q.size()+1;
				loopcount++;
				if (loopcount >= 100) {
					cout << "NA" << endl;
					flg = false;
					break;
				}
			}
			qsize--;
			if (num.first.first == num.second.first && num.first.second == num.second.second) {
				cout << ++loopcount << endl;
				flg = false;
				break;
			}
			for (int i = 0; i < 4; i++) {
				copy.first.first = num.first.first+dx[i];
				copy.first.second = num.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 =num.second.first-dx[i];
				copy.second.second =num.second.second- dy[i];
				if (d[copy.second.first][copy.second.second]) {
					copy.second.first += dx[i];
					copy.second.second += dy[i];
				}
				if (!m[copy]) {
					m[copy] = true;
					q.push(copy);
				}
			}
		}
		if (flg) {
			cout << "NA" << endl;
		}
	}
	return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <algorithm>
#include <math.h>
#include <stack>
#include <string.h>
#include <complex>
using namespace std;

const int INF = 1<<29;
const double EPS = 1e-8;

const int dx[][4] = {{1, 0, -1, 0}, {-1, 0, 1, 0}};
const int dy[][4] = {{0, 1, 0, -1}, {0, -1, 0, 1}};

int X, Y;

bool map[50][50];
bool passed[50][50][50][50];

struct P
{
    int tx, ty;
    int kx, ky;
    int cost;

    P(int _tx, int _ty, int _kx, int _ky, int _cost) : tx(_tx), ty(_ty), kx(_kx), ky(_ky), cost(_cost) {};
};

bool check(int x, int y)
{
    return x < 0 || x >= X || y < 0 || y >= Y || map[y][x];
}

int main()
{
    int tx, ty, kx, ky, ans;
    while(cin >> X >> Y, X|Y)
    {
        ans = -1;
        memset(passed, 0, sizeof passed);
        queue<P> que;

        cin >> tx >> ty >> kx >> ky;
        tx--, ty--, kx--, ky--;

        for(int i = 0; i < Y; i++)
            for(int j = 0; j < X; j++)
                cin >> map[i][j];

        passed[tx][ty][kx][ky] = true;

        for(que.push(P(tx, ty, kx, ky, 0)); !que.empty(); que.pop())
        {
            P p = que.front();

            if(p.cost >= 100)
                break;

            if(p.tx == p.kx && p.ty == p.ky)
            {
                ans = p.cost;
                break;
            }

            for(int i = 0; i < 4; i++)
            {
                int mtx = p.tx + dx[0][i], mty = p.ty + dy[0][i];
                int mkx = p.kx + dx[1][i], mky = p.ky + dy[1][i];

                if(check(mtx, mty))
                    mtx = p.tx, mty = p.ty;
                if(check(mkx, mky))
                    mkx = p.kx, mky = p.ky;
                if(passed[mtx][mty][mkx][mky])
                    continue;

                passed[mtx][mty][mkx][mky] = true;
                que.push(P(mtx, mty, mkx, mky, p.cost + 1));
            }
        }

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

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
using namespace std;
static const double EPS = 1e-5;
typedef long long ll;
typedef pair<int,int> pi;
#define rep(i,n) for(int i=0;i<n;i++)


int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
bool past[50][50][50][50];
int d[50][50];
int x,y;
int tx,ty,kx,ky;


main(){
	while(cin>>x>>y,x){
		cin>>tx>>ty>>kx>>ky;
		--tx;--ty;--kx;--ky;
		
		memset(d,0,sizeof(d));
		rep(i,x)rep(j,y)cin>>d[i][j];
		
		queue<pair<pair<pi,pi>,int> > state;
		memset(past,0,sizeof(past));
		
		state.push(make_pair(make_pair(make_pair(tx,ty),make_pair(kx,ky)),0));
		
		past[tx][ty][kx][ky]=1;
		
		bool na=true;
		
		while(!state.empty()){
			pair<pi,pi> tp=state.front().first;
			int time=state.front().second;
			state.pop();
			if(time>=100)break;
			if(tp.first==tp.second){
				na=false;
				cout<<time<<endl;
				break;
			}
			
			rep(i,4){
				int ttx=tp.first.first+dx[i],tty=tp.first.second+dy[i],
					tkx=tp.second.first-dx[i],tky=tp.second.second-dy[i];
				
				if(ttx<0 || ttx>=x || tty<0 || tty>=y || d[ttx][tty]==1){
					ttx-=dx[i];
					tty-=dy[i];
				}
				if(tkx<0 || tkx>=x || tky<0 || tky>=y || d[tkx][tky]==1){
					tkx+=dx[i];
					tky+=dy[i];
				}
				pair<pair<int,int>,pair<int,int> > next=make_pair(make_pair(ttx,tty),make_pair(tkx,tky));
				
				if(past[ttx][tty][tkx][tky])continue;
				past[ttx][tty][tkx][tky]=1;
				state.push(make_pair(next,time+1));
			}
		}
		
		if(na)puts("NA");
	}
}