Go: package main

import (
	"container/heap"
	"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)
	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)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]struct{}, 0)
	for pq.Len() > 0 {
		now := heap.Pop(&pq).(*Status)
		if now.Person.Distance() == 0 {
			fmt.Println(now.Turn)
			return
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = struct{}{}
		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)
			}
		}
	}
	fmt.Println("NA")
}

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>
#include <set>
using namespace std;

class Node {
public:
  int tx, ty;
  int kx, ky;
  int time;
  Node(int tx = 0, int ty = 0, int kx = 0, int ky = 0, int time = 0):
    tx(tx), ty(ty), kx(kx), ky(ky), time(time) {}

  bool operator <(const Node &n) const {
    if(tx != n.tx) return tx < n.tx;
    if(ty != n.ty) return ty < n.ty;
    if(kx != n.kx) return kx < n.kx;
    if(ky != n.ky) return ky < n.ky;
    return false;
  }
};

int main() {
  while(1) {
    int X, Y;
    cin >> X >> Y;
    if(X == 0 && Y == 0) break;
    int tx, ty;
    cin >> tx >> ty;
    int kx, ky;
    cin >> kx >> ky;
    int data[Y][X];
    for(int i = 0; i < Y; i++) {
      for(int j = 0; j < X; j++) {
	cin >> data[i][j];
      }
    }
    queue<Node> Q;
    set<Node> visited;
    Q.push(Node(tx-1, ty-1, kx-1, ky-1, 0));
    int d[4][2] = {{1,0},{0,1},{-1,0},{0,-1}};
    int ans = -1;
    while(!Q.empty()) {
      Node n = Q.front();
      Q.pop();
      if(visited.find(n) != visited.end()) continue;
      visited.insert(n);
      if(n.tx == n.kx && n.ty == n.ky) {
	ans = n.time;
	break;
      }
      for(int i = 0; i < 4; i++) {
	int ntx = n.tx + d[i][0];
	int nty = n.ty + d[i][1];
	if(ntx < 0 || ntx >= X) ntx = n.tx;
	if(nty < 0 || nty >= Y) nty = n.ty;
	if(data[nty][ntx] == 1) {
	  ntx = n.tx;
	  nty = n.ty;
	}
	int nkx = n.kx - d[i][0];
	int nky = n.ky - d[i][1];
	if(nkx < 0 || nkx >= X) nkx = n.kx;
	if(nky < 0 || nky >= Y) nky = n.ky;
	if(data[nky][nkx] == 1) {
	  nkx = n.kx;
	  nky = n.ky;
	}
	if(visited.find(Node(ntx, nty, nkx, nky, n.time+1)) == visited.end())
	  Q.push(Node(ntx, nty, nkx, nky, n.time+1));
      }
    }
    if(ans == -1) {
      cout << "NA" << endl;
    } else {
      cout << ans << endl;
    }
  }
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <complex>
#include <cstring>
#include <cstdlib>
#include <string>
#include <cmath>
#include <queue>
#include <map>
using namespace std;

#define REP(i,n) for(int i=0;i<(int)n;++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
const int INF = 1<<29;

typedef pair<int,int> pii;
typedef pair<pii, pii> piiii;

int X, Y;
int ba[50][50];

int dtx[] = {0,1,0,-1};
int dty[] = {-1,0,1,0};
int dkx[] = {0,-1,0,1};
int dky[] = {1,0,-1,0};

map<piiii, bool> visited;

int solve(pii T, pii K) {
  queue<pair<piiii, int> > Q;
  Q.push(make_pair(piiii(T,K), 0));
  while(Q.size()) {
    pii tt = Q.front().first.first, kk = Q.front().first.second;
    int m = Q.front().second;
    Q.pop();
    if (m >= 100) break;
    if (tt == kk) return m;
    visited[piiii(tt,kk)] = true;
//    cout << tt.first << ","<<tt.second<<" " << kk.first<<","<<kk.second << endl;
    REP(k,4) {
      int txx = tt.first + dtx[k];
      int tyy = tt.second + dty[k];
      int kxx = kk.first + dkx[k];
      int kyy = kk.second + dky[k];

      if (txx < 0 || X <= txx || tyy < 0 || Y <= tyy || ba[txx][tyy]) {
        txx -= dtx[k];
        tyy -= dty[k];
      }
      if (kxx < 0 || X <= kxx || kyy < 0 || Y <= kyy || ba[kxx][kyy]) {
        kxx -= dkx[k];
        kyy -= dky[k];
      }
      if (!visited[piiii(pii(txx, tyy),pii(kxx, kyy))])
        Q.push(make_pair(piiii(pii(txx, tyy), pii(kxx, kyy)), m+1));
    }
  }
  return -1;
}

int main() {
  while(cin >> X >> Y, X||Y) {
    int tx, ty, kx, ky;
    cin >> tx >> ty;
    cin >> kx >> ky;
    tx--;ty--;kx--;ky--;
    REP(y,Y)
      REP(x,X)
        cin >> ba[x][y];
    int res = solve(pii(tx,ty), pii(kx,ky));
    if (res < 0)
      cout << "NA" << endl;
    else
      cout << res << endl;
  }
}