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 ans <= now.Turn {
			continue
		}
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if v, ok := memo[now.Person]; ok && v <= 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<iostream>
#include<queue>

using namespace std;

#define MAX 51

int xy[MAX][MAX];
int cost[MAX][MAX][MAX][MAX];
int X,Y;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

struct state{
  int tx;
  int ty;
  int kx;
  int ky;
  int co;
  state(){}
  state(int tx,int ty,int kx,int ky,int co):
    tx(tx),ty(ty),kx(kx),ky(ky),co(co){}
};

int solve(int tx,int ty,int kx,int ky){

  memset(cost,101,sizeof(cost));

  queue<state> q;
  q.push( state(tx,ty,kx,ky,0) );

  while( !q.empty() ){
    state p=q.front();
    q.pop();

    //printf("co=%d\n",p.co);

    if(p.co==100){
      break;
    }

    tx=p.tx;
    ty=p.ty;
    kx=p.kx;
    ky=p.ky;

    for(int i=0;i<4;i++){
     
      /*  if( (tx+dx[i] < 0 || ty+dy[i] <0 || tx+dx[i] >= X || ty+dy[i] >= Y) || xy[ty+dy[i]][tx+dx[i]]==1 ){
	fl++;
      }
      if(kx+dx[i]*-1 < 0 || ky+dy[i]*-1 <0 || kx+dx[i]*-1 >= X || ty+dy[i]*-1 >= Y || xy[ky+dy[i]*-1][kx+dx[i]*-1]==1){
	fl+=10;
	}*/

      
      if(kx+dx[i]*-1 < 0 || ky+dy[i]*-1 <0 || kx+dx[i]*-1 >= X || ty+dy[i]*-1 >= Y || 
	 tx+dx[i] < 0 || ty+dy[i] <0 || tx+dx[i] >= X || ty+dy[i] >= Y )
	continue;

      cost[tx][ty][kx][ky]=p.co;

      if( cost[tx+dx[i]][ty+dy[i]][kx+dx[i]*-1][ky+dy[i]*-1] < p.co)
	continue;

      if( xy[ty+dy[i]][tx+dx[i]]==1 || xy[ky+dy[i]*-1][kx+dx[i]*-1]==1 )
	continue;
      
      if(tx+dx[i] == kx+dx[i]*-1 && ty+dy[i] == ky+dy[i]*-1){
	if(p.co+1>=100) return -1;
	return p.co+1;
      }

      //if(cost[p.tx+dx[i]][p.ty+dy[i]] < p.co)
      //continue;
      //if(cosk[p.kx+dx[i]*-1][p.ky+dy[i]*-1] < p.co)
      //continue;

      //cost[p.tx+dx[i]][p.ty+dy[i]]=p.co+1;
      //cosk[p.kx+dx[i]*-1][p.ky+dy[i]*-1]=p.co+1;

      /*if(fl%10==1 && fl/10==1)
	continue;
      else if(fl%10==1)
	q.push( state(tx+dx[i],ty+dy[i],kx,ky,p.co+1) );
      else if(fl/10==1)
      q.push( state(tx,ty,kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );
      else*/

      q.push( state(tx+dx[i],ty+dy[i],kx+dx[i]*-1,ky+dy[i]*-1,p.co+1) );

    }
  }
  return -1;
} 

main(){
  
  int i,j;
  int kx,ky,tx,ty;
  int n;

  while(1){
    
    cin >> X >> Y;

    if(X==0 && Y==0) break;
    
    cin >> tx >> ty;
    cin >> kx >> ky;
    
    for(i=0;i<Y;i++){
      for(j=0;j<X;j++){
	cin >> xy[i][j];
      }
    }
    
    n=solve(tx-1,ty-1,kx-1,ky-1);
    
    if(n==-1)
      cout << "NA" << endl;
    else
      cout << n << endl;
  }
  return 0;
}

C++: #include <cstdio>
#include <set>
#include <queue>
#include <cstring>
using namespace std;
typedef pair<int,int> pos;
typedef pair<pos,pos> two;
typedef pair<int,two> node;
int map[52][52];
int next[4][4] = {
  { 1, 0, -1, 0 },
  {-1, 0,  1, 0 },
  { 0, 1,  0,-1 },
  { 0,-1,  0, 1 },
};
int main()
{
  for(;;){
    int x,y,tx,ty,kx,ky;
    scanf("%d %d",&x,&y);
    if(x == 0 || y == 0) break;
    memset(map,0,sizeof(map));
    scanf("%d %d",&tx,&ty);
    scanf("%d %d",&kx,&ky);
    set<two> memo;
    two t = make_pair(make_pair(tx,ty),make_pair(kx,ky));
    memo.insert(t);
    queue<node> q;
    node n = make_pair(0,t);
    q.push(n);
    int i,j;
    for(i=1; i<=y; i++){
      for(j=1; j<=x; j++){
        int n;
        scanf("%d",&n);
        map[i][j] = n;
      }
    }
    for(;;){
      if(q.empty()){
        printf("NA\n");
        break;
      }
      node n = q.front();
      q.pop();
      if(n.first > 100){
        printf("NA\n");
        break;
      }
      pos t = n.second.first;
      pos k = n.second.second;
      if(t == k){
        printf("%d\n",n.first);
        break;
      }
      two temp;
      for(int i=0; i<4; i++){
        pos tn = make_pair(t.first+next[i][0], t.second+next[i][1]);
        pos kn = make_pair(k.first+next[i][2], k.second+next[i][3]);
        bool bt = true, bk = true;
        if(tn.second == 0 || tn.second > y || tn.first == 0 || tn.first > x ||
           map[tn.second][tn.first] == 1) bt = false;
        if(kn.second == 0 || kn.second > y || kn.first == 0 || kn.first > x ||
           map[kn.second][kn.first] == 1) bk = false;
        if(!bt && !bk){
          continue;
        }else if(!bt){
          temp = make_pair(t,kn);
        }else if(!bk){
          temp = make_pair(tn,k);
        }else{
          temp = make_pair(tn,kn);
        }
        if(memo.insert(temp).second){
          node nd = make_pair(n.first+1,temp);
          q.push(nd);
        }
      }
    }
  }
  return 0;
}