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 <iostream>
#include <queue>
#include <functional>
#include <algorithm>
using namespace std;

const int INF = 100;
const int MAX = 50;
const int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
int field[MAX][MAX];
bool visited[MAX][MAX][MAX][MAX];

typedef pair<int, int> P;
typedef pair<P, P> Q;
typedef pair<int, Q> S;

bool check(int x, int y, int w, int h)
{
    return(x >= 0 && x < w && y >= 0 && y < h && field[y][x] == 0);
}

int main()
{
    int w, h, tx, ty, kx, ky;
    while(cin >> w >> h && w) {

        cin >> tx >> ty >> kx >> ky;
        for(int i = 0; i < h; i++) {
            for(int j = 0; j < w; j++) {
                cin >> field[i][j];
                for(int k = 0; k < h; k++) 
                    for(int l = 0; l < w; l++)
                        visited[i][j][k][l] = false;
            }
        }

        queue<S> que;
        int min = INF;
        que.push(S(0, Q( P(tx - 1, ty - 1), P(kx - 1, ky - 1))));
        while(!que.empty()) {
            S s = que.front(); que.pop();
            int x1, y1, x2, y2, step;
            step = s.first;
            x1 = s.second.first.first;
            y1 = s.second.first.second;
            x2 = s.second.second.first;
            y2 = s.second.second.second;
            
            if(x1 == x2 && y1 == y2) {
                min = step;
                break;
            }

            for(int k = 0; k < 4; k++) {
                int nx1, ny1, nx2, ny2;
                nx1 = x1 + dx[k];
                ny1 = y1 + dy[k];
                nx2 = x2 - dx[k];
                ny2 = y2 - dy[k];
                if(!check(nx1, ny1, w, h)) {
                    nx1 = x1;
                    ny1 = y1;
                }
                if(!check(nx2, ny2, w, h)) {
                    nx2 = x2;
                    ny2 = y2;
                }

                if(visited[nx1][ny1][nx2][ny2])
                    continue;
                visited[nx1][ny1][nx2][ny2] = true;
                que.push(S(step + 1, Q(P(nx1, ny1), P(nx2, ny2))));
            }
        }
        if(min == INF)
            cout << "NA" << endl;
        else 
            cout << min << endl;
    }
    
}

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

struct S {
	int tx,ty;
	int kx,ky;
	int turn;
	S(int tx,int ty,int kx,int ky,int turn);
};

S::S(int _tx,int _ty,int _kx,int _ky,int _turn) {
	tx=_tx;
	ty=_ty;
	kx=_kx;
	ky=_ky;
	turn=_turn;
}

bool d[50][50];
bool vst[50][50][50][50];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	while(cin>>X>>Y,X||Y) {
		cin>>tx>>ty>>kx>>ky;
		for(int j=0;j<Y;j++) {
			for(int i=0;i<X;i++) {
				cin>>d[i][j];
			}
		}
		tx--;ty--;kx--;ky--;
		queue<S> q;
		bool ok=false;
		q.push(S(tx,ty,kx,ky,0));
		memset(vst,false,sizeof(vst));
		vst[tx][ty][kx][ky]=true;
		while(!q.empty()) {
			S s=q.front();q.pop();
			if(s.turn>=100) break;
			if(s.tx==s.kx&&s.ty==s.ky) {
				cout<<s.turn<<endl;
				ok=true;
				break;
			}
			for(int i=0;i<4;i++) {
				int ntx=s.tx+dx[i],nty=s.ty+dy[i];
				int nkx=s.kx-dx[i],nky=s.ky-dy[i];
				if(0>ntx||ntx>=X||0>nty||nty>=Y||d[ntx][nty]) {
					ntx-=dx[i],nty-=dy[i];
				}
				if(0>nkx||nkx>=X||0>nky||nky>=Y||d[nkx][nky]) {
					nkx+=dx[i],nky+=dy[i];
				}
				if(!vst[ntx][nty][nkx][nky]) {
					vst[ntx][nty][nkx][nky]=true;
					q.push(S(ntx,nty,nkx,nky,s.turn+1));
				}
			}
		}
		if(!ok) cout<<"NA"<<endl;
	}
	return 0;
}