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 (pq PQStatus) Len() int {
	return len(pq)
}
func (pq PQStatus) Less(i, j int) bool {
	if pq[i].Turn == pq[j].Turn {
		return pq[i].Person.Distance() < pq[j].Person.Distance()
	}
	return pq[i].Turn < pq[j].Turn
}

func (pq PQStatus) Swap(i, j int) {
	pq[i], pq[j] = pq[j], pq[i]
}

func (pq *PQStatus) Push(x interface{}) {
	item := x.(*Status)
	*pq = append(*pq, item)
}

func (pq *PQStatus) Pop() interface{} {
	old := *pq
	n := len(old)
	item := old[n-1]
	*pq = old[0 : n-1]
	return item
}

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)
	//heap.Init(&pq)
	//heap.Push(&pq, start)
	pq.Push(start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(101)
	for pq.Len() > 0 {
		//now := heap.Pop(&pq).(*Status)
		now := pq.Pop().(*Status)
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if v, ok := memo[now.Person]; ok && v <= now.Turn {
			continue
		}
		if ans<=now.Turn {
			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 += 1
			if next.Turn < 100 {
				//heap.Push(&pq, next)
				pq.Push(next)
			}
		}
	}
	if ans == 101 {
		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 F first
#define S second
#define MP make_pair
#define pb push_back
#define endl '\n'

using namespace std;

typedef long long LL;
typedef pair< int, int > P;
typedef pair< LL, LL > LP;
typedef pair< int, P > iP;
typedef pair< P, P > PP;

static const int INF = INT_MAX;
static const LL LINF = LLONG_MAX;
static const int MIN = INT_MIN;
static const LL LMIN = LLONG_MIN;
static const int MOD = 1000000007;
static const int SIZE = 100005;

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

int bfs( P t_pos, P k_pos );

queue< pair< pair< P, P >, int > > q;
int mp[100][100];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    while( true ) {
        int h, w;
        cin >> w >> h;
        if( h == 0 && w == 0 ) break;
        P t, k;
        cin >> t.S >> t.F >> k.S >> k.F;
        for( int i = 0; i < 55; ++i ) {
            for( int j = 0; j < 55; ++j ) mp[i][j] = 1;

        }

        for( int i = 1; i <= h; ++i ) {
            for( int j = 1; j <= w; ++j ) {
                cin >> mp[i][j];

            }
        }

        int res = bfs( t, k );
        if( res == -1 ) cout << "NA";
        else cout << res;
        cout << endl;

    }
    return 0;
}


int bfs( P t_pos, P k_pos ) {

    map< pair< P, P >, int > visit;
    visit[MP( t_pos, k_pos )] = 1;
    while( !q.empty() ) q.pop();

    q.push( MP( MP( t_pos, k_pos ), 0 ) );

    while( !q.empty() ) {
        pair< pair< P, P >, int > p = q.front();
        q.pop();
        if( p.F.F.F == p.F.S.F && p.F.F.S == p.F.S.S ) return p.S;
        if( p.S == 100 ) continue;

        for( int i = 0; i < 4; ++i ) {
            P t_pos = p.F.F;
            P k_pos = p.F.S;
            bool flg = false;
            if( mp[t_pos.F + dx[i]][t_pos.S + dy[i]] == 0 ) {
                t_pos.F += dx[i]; t_pos.S += dy[i];
                flg = true;

            }

            if( mp[k_pos.F - dx[i]][k_pos.S - dy[i]] == 0 ) {
                k_pos.F -= dx[i]; k_pos.S -= dy[i];
                flg = true;

            }
            
            if( visit[MP( t_pos, k_pos )] == 1 ) continue;
            if( t_pos.F == k_pos.F && t_pos.S == k_pos.S ) {
                return p.S + 1;

            }
            if( flg ) {
                visit[MP( t_pos, k_pos )] = 1;
                q.push( MP( MP( t_pos, k_pos ), p.S + 1 ) );

            }
        }
    }

    return -1;
}

C++: #include<iostream>
#include<queue>
#include<cstring>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int w,h;
PP S;
int A[52][52][52][52],D[52][52];
int main(){
	queue<PP> P;
	int d=0,i=0,j=0,l=-1;
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	cin>>w>>h;
	while(w!=0||h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1;
		}
	}

	cin>>S.tx>>S.ty;
	cin>>S.kx>>S.ky;
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		cin>>D[i][j];
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			cout<<S.Z;
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			cout<<"NA"<<endl;
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.ty][S.tx][S.ky][S.kx]==1||(D[S.ty][S.tx]==1&&D[S.ky][S.kx]==1)){
			continue;
		}
		A[S.ty][S.tx][S.ky][S.kx]=1;

		if(D[S.ty][S.tx]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.ky][S.kx]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		//saka();
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			cout<<S.Z<<endl;
			break;
		}	
		if(S.Z==101){
			cout<<"NA"<<endl;
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	d=0;
	l=-1;
	cin>>w>>h;
	}	
	return 0;

}