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 := 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<queue>
#include<iostream>
#include<algorithm>
using namespace std;
bool same[52][52][52][52] = { 0 };
struct maigo{
	int x[2];// ????????????[0]???????????????[1]
	int y[2];// ????????????[0]???????????????[1]
	int count;
};
queue<maigo> q;
int main(){
	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){
		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();
			same[t.x[0]][t.y[0]][t.x[1]][t.y[1]] = 1;
			if (t.count >= 100) 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]][t.y[1] - dx2[i]] == 0 &&
					same[t.x[0] + dx1[i]][t.y[0] + dx2[i]][t.x[1] - dx1[i]][t.y[1] - dx2[i]] == 0){
					if (t.x[0] + dx1[i] == t.x[1] - dx1[i] &&
						t.y[0] + dx2[i] == t.y[1] - dx2[i]){
						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], into.y[1] = t.y[1] - dx2[i];

					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]][t.y[1] - dx2[i]] != 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];

					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]][t.y[1] - dx2[i]] == 0 &&
					same[t.x[0]][t.y[0]][t.x[1] - dx1[i]][t.y[1] - dx2[i] == 0]){
					if (t.x[0] == t.x[1] - dx1[i] &&
						t.y[0] == t.y[1] - dx2[i]){
						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], into.y[1] = t.y[1] - dx2[i];
					into.count = t.count + 1;
					q.push(into);
				}
			}
		}if (flag == 0) {
			cout << "NA" << endl;
		}while (!q.empty()) q.pop();
		flag = 0;
		fill(same[0][0][0], same[52][0][0], 0);
		cin >> X >> Y;
	}
	return 0;
}

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

const int INF = 1<<29;
const double EPS = 1e-8;
typedef vector<int> vec;
typedef pair<int,int> P;

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

struct node{
    int d,tx,ty,kx,ky;
};

int d[50][50][50][50];
int field[50][50];
int X,Y;

void print(node& p){
    for(int i=0;i<Y;i++){
        for(int j=0;j<X;j++){
            if(i==p.ty&&j==p.tx) cout << 't';
            else if(i==p.ky&&j==p.kx) cout << 'k';
            else cout << field[i][j];
        }
        cout << endl;
    }
    cout << endl;
}

int main(){
    while(1){
        scanf("%d%d",&X,&Y);
        if(!X)break;

        int tx,ty,kx,ky;
        scanf("%d%d%d%d",&tx,&ty,&kx,&ky);
        tx--;ty--;kx--;ky--;

        for(int i=0;i<Y;i++){
            for(int j=0;j<X;j++){
                scanf("%d",&field[i][j]);
            }
        }

        for(int i=0;i<Y;i++){
            for(int j=0;j<X;j++){
                for(int k=0;k<Y;k++){
                    for(int l=0;l<X;l++){
                        d[i][j][k][l] = INF;
                    }
                }
            }
        }

        queue<node> que;
        d[tx][ty][kx][ky] = 0;
        que.push((node){0,tx,ty,kx,ky});
        bool not_reach = true;
        while(que.size()){
            node p = que.front(); que.pop();
            if(p.d>=100)break;
            if(p.tx==p.kx&&p.ty==p.ky){
                cout << p.d << endl;
                not_reach = false;
                break;
            }
            for(int i=0;i<4;i++){
                int n_tx = p.tx+dx[i], n_ty = p.ty+dy[i];
                int n_kx = p.kx-dx[i], n_ky = p.ky-dy[i];
                if(n_tx<0||X<=n_tx||n_ty<0||Y<=n_ty||field[n_ty][n_tx]){
                    n_tx = p.tx; n_ty = p.ty;
                }
                if(n_kx<0||X<=n_kx||n_ky<0||Y<=n_ky||field[n_ky][n_kx]){
                    n_kx = p.kx; n_ky = p.ky;
                }
                if(d[n_tx][n_ty][n_kx][n_ky]>p.d+1){
                    d[n_tx][n_ty][n_kx][n_ky] = p.d+1;
                    que.push((node){p.d+1,n_tx,n_ty,n_kx,n_ky});
                }
            }
        }
        if(not_reach)cout << "NA" << endl;
    }
    return 0;
}