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 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)
			}
		}
	}
	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 <bits/stdc++.h>
using namespace std;

int table[51][51];

bool memo[51][51][51][51];

const int leftmove = -1;
const int rightmove = 1;
const int upmove = -1;
const int downmove = 1;

int main() {

    while(1){

        int w,h;

        //scanf(" %d %d",&w,&h);

        cin >> w >> h;

        if(w==0&&h==0) break;

        int tx,ty,kx,ky;

        //scanf(" %d %d %d %d",&tx,&ty,&kx,&ky);

        cin >> tx >> ty >> kx >> ky;

        for(int i=1;i<51;i++){
            for(int j=1;j<51;j++){
                table[i][j] = 1;
                for(int k=0;k<51;k++){
                    for(int r=0;r<51;r++){
                        memo[i][j][k][r] = false;
                    }
                }
            }
        }

        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                //scanf(" %d",&table[i][j]);
                cin >> table[j][i];
            }
        }

        /*printf("\n");

        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                printf("%d ",table[i][j]);
            }
            printf("\n");
        }*/

        //memset(memo,false,sizeof(memo));

        queue<vector<int> > q;

        vector<int> v(5);

        v[0] = tx; v[1] = ty; v[2] = kx; v[3] = ky; v[4] = 0;

        if(table[v[0]][v[1]] == 1 || table[v[2]][v[3]] == 1){
            cout << "NA" << endl;
            continue;
        }

        q.push(v);

        bool check = false;

        while(!q.empty()){

            v = q.front(); q.pop();

            if(memo[v[0]][v[1]][v[2]][v[3]]){
                continue;
            }

            if(v[0] == v[2] && v[1] == v[3]){
                check = true;
                cout << v[4] << endl;
                break;
            }

            memo[v[0]][v[1]][v[2]][v[3]] = true;

            v[4]++;

            if(v[4] >= 100){
                break;
            }

            vector<int> before(5);

            for(int i=0;i<5;i++){
                before[i] = v[i];
            }

            if(v[0]+leftmove != -1 && table[v[0]+leftmove][v[1]] == 0){
                v[0]+=leftmove;
            }
            if(v[2]+rightmove != w+1 && table[v[2]+rightmove][v[3]] == 0){
                v[2]+=rightmove;
            }

            q.push(v);

            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            if(v[2]+leftmove != -1 && table[v[2]+leftmove][v[3]] == 0){
                v[2]+=leftmove;
            }
            if(v[0]+rightmove != w+1 && table[v[0]+rightmove][v[1]] == 0){
                v[0]+=rightmove;
            }

            q.push(v);


            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            if(v[3]+upmove != -1 && table[v[2]][v[3]+downmove] == 0){
                v[3]+=upmove;
            }
            if(v[1]+downmove != h+1 || table[v[0]][v[1]+upmove] == 0){
                v[1]+=downmove;
            }

            q.push(v);

            for(int i=0;i<5;i++){
                v[i] = before[i];
            }

            if(v[1]+upmove != -1 && table[v[0]][v[1]+upmove] == 0){
                v[1]+=upmove;
            }
            if(v[3]+downmove != h+1 && table[v[2]][v[3]] == 0){
                v[3]+=downmove;
            }

             q.push(v);
        }

        if(!check){
            cout << "NA" << endl;
        }



    }

    return 0;
}

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

int x,y,tx,ty,kx,ky,cou;
int mas[111][111];
int ans=0;
bool used[111][111][111][111];
int dx[]={-1,0,0,1};
int dy[]={0,-1,1,0};
struct P{
  int tx,ty,kx,ky,cou;
  P(int tx,int ty,int kx,int ky,int cou):tx(tx),ty(ty),kx(kx),ky(ky),cou(cou){}
};
int bfs();

int main(){
  while(1){
    cin >> x >> y;
    if(x==0 && y==0) break;
    memset(used,false,sizeof(used));
    cin >> tx >> ty;
    cin >> kx >> ky;
    for(int i=0;i<y;i++){
      for(int j=0;j<x;j++){
	cin >> mas[i][j];
      }
    }
    ans = bfs();
    if(ans==-1) cout << "NA" << endl;
    else cout << ans << endl;
  }
}

int bfs(){
  queue<P> que;
  que.push(P(tx-1,ty-1,kx-1,ky-1,0));
  used[tx-1][ty-1][kx-1][ky-1] = true;
  while(!que.empty()){
    P p=que.front();
    if(p.tx==p.kx && p.ty==p.ky) return p.cou;
    else if(p.cou>=100) return -1;
    for(int i=0;i<4;i++){
      int ntx=p.tx+dx[i];
      int nty=p.ty+dy[i];
      int nkx=p.kx+dx[3-i];
      int nky=p.ky+dy[3-i];
      if(ntx<0 || ntx>=x || nty<0 || nty>=y || mas[nty][ntx]==1){
	ntx=p.tx;
	nty=p.ty;
      }
      if(nkx<0 || nkx>=x || nky<0 || nky>=y || mas[nky][nkx]==1){
	nkx=p.kx;
	nky=p.ky;
      }
      if(used[ntx][nty][nkx][nky]==false){
	que.push(P(ntx,nty,nkx,nky,p.cou+1));
	used[ntx][nty][nkx][nky] = true;
      }
    }
    que.pop();
  }
  return -1;
}