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++:   State(int a,int b,int c,int d):a(a),b(b),c(c),d(d){};
};

int h,w;
int table[51][51],memo[51][51][51][51];
int Y[4]={-1,0,1,0};
int X[4]={0,1,0,-1};

bool in(int a,int b){
  if(a<0 || b<0 || h<=a || w<=b)return false;
  return true;
}

void init(){
  for(int i=0;i<51;i++)
    for(int j=0;j<51;j++)
      for(int k=0;k<51;k++)
	for(int l=0;l<51;l++)memo[i][j][k][l]=inf;
}

int main()
{
  int a,b,c,d;
  while(1){
    cin>>w>>h;
    if(h+w==0)break;
    cin>>b>>a>>d>>c;
    a--;b--;c--;d--;
    for(int i=0;i<h;i++)for(int j=0;j<w;j++)cin>>table[i][j];
    init();

    queue<State> q;
    q.push(State(a,b,c,d));
    memo[a][b][c][d]=0;

    int ans=inf;
    while(!q.empty()){
      State u=q.front();
      q.pop();

      if(u.a==u.c && u.b==u.d){
	ans=min(memo[u.a][u.b][u.c][u.d],ans);
        continue;
      }

      if(memo[u.a][u.b][u.c][u.d]>=100)continue;

      for(int i=0;i<4;i++){
	int A=u.a+Y[i],B=u.b+X[i],C=u.c+Y[(i+2)%4],D=u.d+X[(i+2)%4];
	if(table[A][B] || !in(A,B)){
	  A=u.a;
	  B=u.b;
	}
	if(table[C][D] || !in(C,D)){
	  C=u.c;
	  D=u.d;
	}
	if(memo[A][B][C][D]>memo[u.a][u.b][u.c][u.d]+1){
	  q.push(State(A,B,C,D));
	  memo[A][B][C][D]=memo[u.a][u.b][u.c][u.d]+1;
	}
      }
    }
    if(ans>=100)cout<<"NA"<<endl;
    else cout<<ans<<endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <iterator>
#include <cstdlib>
#include <algorithm>
using namespace std;

typedef vector<int> vint;

vint input(int sz){
	string s;
	getline(cin, s);
	stringstream ss1(s), ss2;
	istream_iterator<int> b(ss1), e;
	vint v(b, e);
	if(cin.eof() || v.size() != sz){ throw ""; }
	for(int i = 0; i < sz; ++i){
		if(i){ ss2 << ' '; }
		ss2 << v[i];
	}
	string t = ss2.str();
	if(s != t){ throw 0; }
	return v;
}

int main(){
	while(1){
		vint v = input(2);
		if(!v[0] && !v[1]){ break; }
		input(2);
		input(2);
		for(int i = 0; i < v[1]; ++i){
			input(v[0]);
		}
	}

	cin.peek();
	if(!cin.eof()){
		exit(EXIT_FAILURE);
	}
}

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

const int INF =100000000;

class Point{
public:
  int tx;
  int ty;
  int kx;
  int ky;
  int cost;
};

int main(){
  int N,M;
  while(cin>>N>>M,N || M){
      int o_tx,o_ty;
      int o_kx,o_ky;
      cin>>o_tx>>o_ty;
      cin>>o_kx>>o_ky;
      int F[52][52];
      for(int y=0;y<=N+1;y++){
        for(int x=0;x<=M+1;x++){
          F[y][x]=1;
        }
      }

      for(int y=1;y<=N;y++){
        for(int x=1;x<=M;x++){
          cin>>F[y][x];
        }
      }

      bool same_pos[52][52][52][52];
      for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
          for(int k=1;k<=N;k++){
            for(int q=1;q<=M;q++){
              same_pos[i][j][k][q]=false;
            }
          }
        }
      }
      queue<Point> que;
      Point p;
      p.tx=o_tx;p.ty=o_ty;
      p.kx=o_kx;p.ky=o_ky;
      que.push(p);
      p.cost=0;

      while(!que.empty()){
        p=que.front();que.pop();
        if(same_pos[p.ty][p.tx][p.ky][p.kx])continue;
        same_pos[p.ty][p.tx][p.ky][p.kx]=true;
        if(p.cost==100)break;
        if(p.tx==p.kx&&p.ty==p.ky){
          cout<<p.cost<<endl;
          break;
        }
        if(F[p.ty-1][p.tx]!=1 || F[p.ky+1][p.kx]!=1){
          Point q;
          if(F[p.ty-1][p.ty]!=1){
            q.tx=p.tx;q.ty=p.ty-1;
          }
          else{
            q.tx=p.tx;q.ty=p.ty;
          }
          if(F[p.ky+1][p.kx]!=1){
            q.kx=p.kx;q.ky=p.ky+1;
          }
          else{
            q.kx=p.kx;q.ky=p.ky;
          }
          q.cost=p.cost+1;
          que.push(q);

        }
        if(F[p.ty+1][p.tx]!=1 || F[p.ky-1][p.kx]!=1){
          Point q;
          if(F[p.ty+1][p.tx]!=1){
            q.tx=p.tx;q.ty=p.ty+1;
          }
          else{
            q.tx=p.tx;q.ty=p.ty;
          }
          if(F[p.ky-1][p.kx]!=1){
            q.kx=p.kx;q.ky=p.ky-1;
          }
          else{
            q.kx=p.kx;q.ky=p.ky;
          }
          q.cost=p.cost+1;
          que.push(q);
        }
        if(F[p.ty][p.tx-1]!=1 || F[p.ky][p.kx+1]!=1){
          Point q;
          if(F[p.ty][p.tx-1]!=1){
            q.tx=p.tx-1;q.ty=p.ty;
          }
          else{
            q.tx=p.tx;q.ty=p.ty;
          }
          if(F[p.ky][p.kx+1]!=1){
            q.kx=p.kx+1;q.ky=p.ky;
          }
          else{
            q.kx=p.kx;q.ky=p.ky;
          }
          q.cost=p.cost+1;
          que.push(q);
        }
        if(F[p.ty][p.tx+1]!=1 || F[p.ky][p.kx-1]!=1){
          Point q;
          if(F[p.ty][p.tx+1]!=1){
            q.tx=p.tx+1;q.ty=p.ty;
          }
          else{
            q.tx=p.tx;q.ty=p.ty;
          }
          if(F[p.ky][p.kx-1]!=1){
            q.kx=p.kx-1;q.ky=p.ky;
          }
          else{
            q.kx=p.kx;q.ky=p.ky;
          }
          q.cost=p.cost+1;
          que.push(q);
        }
      }
      if(p.tx!=p.kx || p.ty!=p.ky){
        cout<<"NA"<<endl;
      }
    }
  return 0;
}