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 <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cassert>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
using namespace std;
typedef pair<int,int> P;
typedef pair<int,P> P1;
typedef pair<P,P> P2;
typedef long long ll;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define fi first
#define sc second
#define rep(i,x) for(int i=0;i<x;i++)
int dp[55][55][55][55];
bool u[55][55][55][55];
int main()
{
	while(1)
	{
		int x,y;
		int ax,ay;
		int bx,by;
		cin >> x >> y; if(x == 0) return 0;
		cin >> ax >> ay; ax--; ay--;
		cin >> bx >> by; bx--; by--;
		int f[55][55];
		for(int i=0;i<y;i++)
		{
			for(int j=0;j<x;j++)
			{
				cin >> f[i][j];
			}
		}
		for(int i=0;i<55;i++) for(int j=0;j<55;j++) for(int k=0;k<55;k++) for(int l=0;l<55;l++) dp[i][j][k][l] = INF,u[i][j][k][l] = 0;
		dp[ay][ax][by][bx] = 0;
		queue<P2>que;
		que.push(mp(mp(ay,ax),mp(by,bx)));
		while(!que.empty())
		{
			P2 p = que.front(); que.pop();
			if(u[p.fi.fi][p.fi.sc][p.sc.fi][p.sc.sc]) continue;
			u[p.fi.fi][p.fi.sc][p.sc.fi][p.sc.sc] = true;
			int dx[4]={0,1,0,-1};
			int dy[4]={1,0,-1,0};
			for(int k=0;k<4;k++)
			{
				int ny = p.fi.fi+dy[k];
				int nx = p.fi.sc+dx[k];
				if(0<=ny && ny<y && 0<=nx && nx<x && f[ny][nx]==0)
				{
				}
				else
				{
					ny = p.fi.fi;
					nx = p.fi.sc;
				}
				int ny2 = p.sc.fi+dy[(k+2)%4];
				int nx2 = p.sc.sc+dx[(k+2)%4];
				if(0<=ny2 && ny2<y && 0<=nx2 && nx2<x && f[ny2][nx2]==0)
				{
				}
				else
				{
					ny2 = p.sc.fi;
					nx2 = p.sc.sc;
				}
				if(dp[ny][nx][ny2][nx2] > dp[p.fi.fi][p.fi.sc][p.sc.fi][p.sc.sc]+1)
				{
					dp[ny][nx][ny2][nx2] = dp[p.fi.fi][p.fi.sc][p.sc.fi][p.sc.sc]+1;
					que.push(mp(mp(ny,nx),mp(ny2,nx2)));
				}
			}
		}
		int res = INF;
		for(int i=0;i<y;i++) for(int j=0;j<x;j++) res = min(res,dp[i][j][i][j]);
		if(res >= 100) puts("NA");
		else printf("%d\n",res);
	}
}

C++: #include<iostream>
#include<queue>
#include<map>
using namespace std;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
class state {
public:
	int tx;
	int ty;
	int kx;
	int ky;
	int time;
	bool operator < (const state &s)const {
		if (ty != s.ty)return ty < s.ty;
		if (tx != s.tx)return tx < s.tx;
		if (ky != s.ky)return ky < s.ky;
		if (kx != s.kx)return kx < s.kx;
		return false;
	}
};
int main() {
	int W, H, tx, ty, kx, ky;
	bool d[52][52];
	map<state, bool> m;
	state num;
	state 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.tx = tx;
		num.ty = ty;
		num.kx = kx;
		num.ky = ky;
		num.time = 0;
		queue<state> q;
		q.push(num);
		while (!q.empty()) {
			num = q.front();
			q.pop();
			if (num.time == 100) {
				cout << "NA" << endl;
				break;
			}
			if (num.tx == num.kx && num.ty == num.ky) {
				cout << num.time << endl;
				break;
			}
			for (int i = 0; i < 4; i++) {
				copy = num;
				copy.time++;
				if (!d[num.tx + dx[i]][num.ty + dy[i]]) {
					copy.tx = num.tx + dx[i];
					copy.ty = num.ty + dy[i];
				}
				if (!d[num.kx - dx[i]][num.ky - dy[i]]) {
					copy.kx = num.kx - dx[i];
					copy.ky = num.ky - dy[i];
				}
				if (!m[copy]) {
					m[copy] = true;
					q.push(copy);
				}
			}
			if (q.empty()) {
				cout << "NA" << endl;
			}
		}
	}
	return 0;
}

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

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

struct State { int tx, ty, kx, ky, cost; };
int X, Y;
int d[52][52];
bool used[52][52][52][52];

int main() {
    while (cin >> X >> Y, X) {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        for (int i=0; i<=Y+1; ++i) {
            for (int j=0; j<=X+1; ++j) {
                if (i==0 || i==Y+1 || j==0 || j==X+1) d[i][j] = 1;
                else cin >> d[i][j];
            }
        }
        memset(used, false, sizeof used);
        queue<State> q;
        q.push((State){tx, ty, kx, ky, 0});
        int res = -1;
        while ( ! q.empty()) {
            State s = q.front(); q.pop();
            if (used[s.tx][s.ty][s.kx][s.ky]) continue;
            used[s.tx][s.ty][s.kx][s.ky] = true;
            if (s.tx == s.kx && s.ty == s.ky) {
                res = s.cost;
                break;
            }
            for (int i=0; i<4; ++i) {
                if (d[s.ty+dy[i]][s.tx+dx[i]] && d[s.ky-dy[i]][s.kx-dx[i]]) continue;
                int tx2 = s.tx, ty2 = s.ty;
                if ( ! d[s.ty+dy[i]][s.tx+dx[i]]) {
                    tx2 += dx[i];
                    ty2 += dy[i];
                }
                int kx2 = s.kx, ky2 = s.ky;
                if ( ! d[s.ky-dy[i]][s.kx-dx[i]]) {
                    kx2 -= dx[i];
                    ky2 -= dy[i];
                }
                q.push((State){tx2, ty2, kx2, ky2, s.cost+1});
            }
        }
        if (res < 0) {
            cout << "NA" << endl;
        } else {
            cout << res << endl;
        }
    }
    return 0;
}