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
		}
		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;

bool d[50][50][50][50];
int X, Y, tx, ty, kx, ky;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0}, mem[50][50];
int main()
{
loop:
  cin >> X >> Y;
  if(!X)
    return 0;
  cin >> tx >> ty >> kx >> ky;
  tx--; ty--; kx--; ky--;
  for(int y = 0; y < Y; y++)
  {
    for(int x = 0; x < X; x++)
    {
      int a;
      cin >> a;
      mem[y][x] = a;
    }
  }

  queue<int> q;
  q.push(tx);
  q.push(ty);
  q.push(kx);
  q.push(ky);
  q.push(0);
  while(!q.empty())
  {
    int x1 = q.front(); q.pop();
    int y1 = q.front(); q.pop();
    int x2 = q.front(); q.pop();
    int y2 = q.front(); q.pop();
    int n = q.front(); q.pop();
    
    if(n == 100)
    {
      cout << "NA" << endl;
      break;
    }
    
    if(y1 == y2 && x1 == x2)
    {
      cout << n << endl;
      goto loop;
    }

    d[x1][y1][x2][y2] = true;
    d[x2][y2][x1][y1] = true;
    for(int i = 0; i < 4; i++)
    {
      int tx1 = x1 + dx[i];
      int ty1 = y1 + dy[i];
      int tx2 = x2 - dx[i];
      int ty2 = y2 - dy[i];

      bool b1 = ty1 < 0 || ty1 >= Y || tx1 < 0 || tx1 >= X || mem[ty1][tx1] == 1;
      bool b2 = ty2 < 0 || ty2 >= Y || tx2 < 0 || tx2 >= X || mem[ty2][tx2] == 1;

      if(b1)
      {
        tx1 = x1;
        ty1 = y1;
      }
      if(b2)
      {
        tx2 = x2;
        ty2 = y2;
      }
      if(b1 && b2 || d[tx1][ty1][tx2][ty2])
        continue; 

      q.push(tx1);
      q.push(ty1);
      q.push(tx2);
      q.push(ty2);
      q.push(n + 1);
    }
  }
  cout << "NA" << endl;
  goto loop;
}

C++: #include<iostream>
#include<set>
#include<queue>
#include<vector>
#include<sstream>
#include<algorithm>
using namespace std;
#define REP(i,b,n) for(int i=b;i<n;i++)
#define rep(i,n)   REP(i,0,n)
#define pb         push_back

class state{
public:
  int cost;
  int x1,y1,x2,y2;
  bool operator<(const state & a)const{
    if (y1 != a.y1)return y1 < a.y1;
    if (x1 != a.x1)return x1 < a.x1;
    if (x2 != a.x2)return x2 < a.x2;
    if (y2 != a.y2)return y2 < a.y2;
    return false;
  }
};

//bool vis[50][50][50][50];
bool m[100][100];

int dx[] ={0,0,1,-1};
int dy[] ={1,-1,0,0};
int dx2[]={0,0,-1,1};
int dy2[]={-1,1,0,0};

void bfs(int r,int c,int sy,int sx,int gy,int gx){
  set<state> S;
  queue<state> Q;
  S.insert((state){0,sy,sx,gy,gx});
  Q.push((state){0,sy,sx,gy,gx});
  while(!Q.empty()){
    state now = Q.front();Q.pop();
    if (now.cost >= 100)break;
    if (now.x1==now.x2 && now.y1==now.y2){
      cout << now.cost << endl;
      return;
    }

    rep(i,4){
      int nex =now.x1+dx[i] ,ney =now.y1+dy[i];
      int nnex=now.x2+dx2[i],nney=now.y2+dy2[i];
      if (nex ==-1||ney==-1 ||nex==c ||ney==r ||m[ney][nex]){
	nex=now.x1;
	ney=now.y1;
      }
      if (nnex==-1||nney==-1||nnex==c||nney==r||m[nney][nnex]){
	nnex=now.x2;
	nney=now.y2;
      }
      
      //      if (vis[ney][nex][nney][nnex]){
      //	continue;
      //      }
      //      vis[ney][nex][nney][nnex]=true;
      state next=(state){now.cost+1,ney,nex,nney,nnex};
      //Q.push((state){now.cost+1,ney,nex,nney,nnex});
      if (S.find(next) == S.end()){
	S.insert(next);
	Q.push(next);
      }
    }



  }
  cout <<"NA"<<endl;
}

main(){
  int c,r;
  while(cin>>c>>r&& c){
    int sy,sx,gy,gx;
    cin>>sx>>sy>>gx>>gy;
    sx--;sy--;gx--;gy--;
    rep(i,r){
      rep(j,c)cin>>m[i][j];
    }

    bfs(r,c,sy,sx,gy,gx);
  }
}