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)
	pq = append(pq, 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)
		now := pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}
		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)
				pq = append(pq, 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 fst first
#define scd second
#define mp make_pair
#define rep(i,x) for(int i=0;i<(int)x;++i)
#define rep1(i,x) for(int i=1;i<=(int)x;++i)

class P {
public:
    int x, y;
    P (int x0,int y0) {
        x=x0,y=y0;
    };
};

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

int d[53][53];
int memo[53][53][53][53];
bool used[53][53][53][53];

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int X, Y;
    while (cin >> X >> Y, X || Y) {
        int tx, ty; cin >> tx >> ty; tx--; ty--;
        int kx, ky; cin >> kx >> ky; kx--; ky--;
        rep(i, Y) rep(j, X) cin >> d[i][j];

        //rep(i, Y + 2) {
        //    rep(j, X + 2) {
        //        if (j) cout << ' ';
        //        cout << d[i][j];
        //    }
        //    cout << '\n';
        //}

        queue<pair<P, P> > q;

        q.push(mp(P(tx, ty), P(kx, ky)));
        memo[ty][tx][ky][kx] = 0;
        used[ty][tx][ky][kx] = true;

        int ans = -1;

        while (q.size()) {
            pair<P, P> r = q.front(); q.pop();
            P f = r.fst, s = r.scd;

            if (memo[f.y][f.x][s.y][s.x] >= 100) break;

            if (f.x == s.x && f.y == s.y) {
                ans = memo[f.y][f.x][s.y][s.x];
                break;
            }

            rep(i, 4) {
                int nfx = f.x + dx[i], nfy = f.y + dy[i];
                int nsx = s.x - dx[i], nsy = s.y - dy[i];
                if (nfx < 0 || nfx >= X || nfy < 0 || nfy >= Y || d[nfy][nfx] == 1) nfx = f.x, nfy = f.y;
                if (nsx < 0 || nsx >= X || nsy < 0 || nsy >= Y || d[nsy][nsx] == 1) nsx = s.x, nsy = s.y;
                if (!used[nfy][nfx][nsy][nsx]) {
                    used[nfy][nfx][nsy][nsx] = true;
                    memo[nfy][nfx][nsy][nsx] = memo[f.y][f.x][s.y][s.x] + 1;
                    q.push(mp(P(nfx, nfy), P(nsx, nsy)));
                }
            }
        }

        if (ans == -1) cout << "NA" << endl;
        else cout << ans << endl;
    }
}

C++: #include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
typedef struct P{
  int tx,ty,kx,ky,c;
};
int dx[4]={0,1,0,-1};
int dy[4]={-1,0,1,0};
int d[55][55];
int used[55][55][55][55];
int X,Y;
P fa;

queue<P> que;

int main(void){
  int ans;
  while(1){

    scanf("%d %d",&X,&Y);
    if(!X && !Y) break;
    scanf("%d %d %d %d",&fa.tx,&fa.ty,&fa.kx,&fa.ky);
    fa.c=0;
    for(int i=1;i<=Y;i++){
      for(int j=1;j<=X;j++){
	scanf("%d",&d[j][i]);
      }
    }


    ans=-1;
    memset(used,0,sizeof(used));
    que = queue<P>();
    que.push(fa);

    while(!que.empty()){
      P p=que.front();
      que.pop();
      used[p.tx][p.ty][p.kx][p.ky]=1;
      if(p.c>100)break;
      if(p.tx==p.kx && p.ty==p.ky){
	ans=p.c;
	break;
      }
      for(int i=0;i<4;i++){
	int f=0;
	int x[2]={p.tx,p.kx};
	int y[2]={p.ty,p.ky};
	for(int j=0;j<2;j++){
	  int t=1;
	  if(j)t=-1;
	  if(0<x[j]+dx[i]*t && x[j]+dx[i]*t<=X && 0<y[j]+dy[i]*t && y[j]+dy[i]*t<=Y){
	    if(!d[x[j]+dx[i]*t][y[j]+dy[i]*t]){
	      x[j]+=dx[i]*t;
	      y[j]+=dy[i]*t;
	      f+=1;
	    }
	  }
	}
	if(!f)continue;
	if(used[x[0]][y[0]][x[1]][y[1]]){
	  continue;
	}
	P pu={x[0],y[0],x[1],y[1],p.c+1};
	que.push(pu);
      }
    }

    if(ans==-1)puts("NA");
    else printf("%d\n",ans);

  }
}