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<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[50][50][50][50];
int main(){
	PP S;
	queue<PP> P;
	int  w,h;
	int d=0,i=0,j=0,l=-1,D[52][52];
	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};
	scanf("%d %d",&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; //??¨????????????????????\?????? 
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		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.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;

		if(D[S.tx][S.ty]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.kx][S.ky]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

C++: #include<iostream>
#include<queue>

#define fs first
#define sc second
using namespace std;

typedef pair<int,int> P;
typedef pair<P,P> P2;

int x,y;
int mas[50][50][50][50];
int depart[50][50];
int ax,ay,bx,by;

int main(){
  for(;;){
    cin >> x >> y;
    if(!x && !y)break;

    cin >> ax >> ay >> bx >> by;

    for(int i=0;i<y;i++)
      for(int j=0;j<x;j++){
	cin >> depart[i][j];
	for(int k=0;k<y;k++)
	  for(int l=0;l<x;l++)mas[i][j][k][l] = -1;
      }

    mas[ay][ax][by][bx] = 0;
    queue<P2> q;
    q.push(P2(P(ay,ax),P(by,bx)));

    int ans = -1;
    while(q.size()){
      P2 p = q.front();q.pop();
      int ky = p.fs.fs, kx = p.fs.sc;
      int ty = p.sc.fs, tx = p.sc.sc;
      //cout << ky << " " << kx << " " << ty << " " << tx<< endl;
      if(ky==ty && kx==tx){
	ans = mas[ky][kx][ty][tx];
	break;
      }
      if(mas[ky][kx][ty][tx]>=100)break;

      int dx[] = {0,1,0,-1},dy[] = {-1,0,1,0};
      for(int i=0;i<4;i++){
	int sky = ky+dy[i], skx = kx+dx[i];
	int sty = ty-dy[i], stx = tx-dx[i];
	bool f1 = (sky<0 || skx<0 || y<=sky || x<=skx || depart[sky][skx]);
	bool f2 = (sty<0 || stx<0 || y<=sty || x<=stx || depart[sty][stx]);
	if(f1 && f2)continue;
	if(f1 && !f2){
	  sky = ky;
	  skx = kx;
	}
	if(!f1 && f2){
	  sty = ty;
	  stx = tx;
	}
	if(mas[sky][skx][sty][stx]>=0)continue;
	mas[sky][skx][sty][stx] = mas[ky][kx][ty][tx] + 1;
	q.push(P2(P(sky,skx),P(sty,stx)));
      }
    }
    if(ans<0)cout << "NA\n";
    else cout << ans << endl;
  }
}

C++: #include <iostream>
#include <vector>
#include <utility>
#include <queue>
#include <set>
using namespace std;

const int needleX[4] = {-1, 0, 1, 0};
const int needleY[4] = {0, -1, 0, 1};

pair<int, int> newPoint(pair<int, int>& nowPoint, int i, vector<vector<bool> >& depart, bool takayuki){
  pair<int, int> result;
  result.first = nowPoint.first + (needleX[i] * (takayuki ? 1 : -1));
  result.second = nowPoint.second + (needleY[i] * (takayuki ? 1 : -1));
  if(!depart[result.first][result.second]){ result = nowPoint; }
  return result;
}

int main(void){
  while(true){
    int w, h;
    cin >> w >> h;
    if(w == 0 && h == 0){ break; }
    pair<int, int> takayuki, kazuyuki;
    cin >> takayuki.first >> takayuki.second;
    cin >> kazuyuki.first >> kazuyuki.second;

    int input;
    vector<vector<bool> > depart(w + 2, vector<bool>(h + 2, false));
    for(int i = 1; i <= w; i++){
      for(int j = 1; j <= h; j++){
        cin >> input;
        if(input == 0){ depart[i][j] = true; }
      }
    }

    int ans = -1;
    set<pair<pair<int, int>, pair<int, int> > > used;
    queue<pair<int, pair<pair<int, int>, pair<int, int> > > > wait;
    used.insert(make_pair(takayuki, kazuyuki));
    wait.push(make_pair(0, make_pair(takayuki, kazuyuki)));
    while(!wait.empty()){
      int cost = wait.front().first;
      pair<int, int> t = wait.front().second.first;
      pair<int, int> k = wait.front().second.second;
      wait.pop();
      
      if(t == k){
        ans = cost;
        break;
      }

      for(int i = 0; i < 4; i++){
        pair<int, int> newt = newPoint(t, i, depart, true);
        pair<int, int> newk = newPoint(k, i, depart, false);
        if(used.count(make_pair(newt, newk)) == 0){
          used.insert(make_pair(newt, newk));
          wait.push(make_pair(cost + 1, make_pair(newt, newk)));
        }
      }
    }
    
    if(ans == -1){ cout << "NA" << endl; }
    else{ cout << ans << endl; }
  }
  
  return 0;
}