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 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)
	pq = append(pq, start)
	dx := []int64{0, 1, 0, -1}
	dy := []int64{1, 0, -1, 0}
	memo := make(map[PersonPosition]int64, 0)
	ans := int64(102)
	for len(pq) > 0 {
		now := &Status{}
		*now = *pq[0]
		pq = pq[1:]
		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = now.Turn
		}
		if ans <= now.Turn {
			continue
		}

		if _, ok := memo[now.Person]; ok {
			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++
			if next.Turn <= 100 {
				pq = append(pq, next)
			}
		}
	}
	if ans == 102 {
		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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <sstream>
#include <cassert>
#include <list>
using namespace std;
static const double EPS = 1e-8;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PI;
#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()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define SZ(a) (int(a.size()))
#define F first
#define S second
const double pi=acos(-1);
int dx[]={0,1,0,-1},dy[]={1,0,-1,0};

int X,Y,tx,ty,kx,ky;
int wall[50][50];
bool vis[50][50][50][50];

typedef struct _node{
  int cost,tx,ty,kx,ky;
  int geth()const{
    return (abs(tx-kx)+abs(ty-ky))/2;
  }
  bool operator<(const _node& r)const{
    return cost>r.cost;
    return cost+geth()>r.cost+r.geth();
  }
  _node (int c,int atx,int aty,int akx,int aky){
    cost=c;
    tx=atx;
    ty=aty;
    kx=akx;
    ky=aky;
  }
}node;

void solve(){
  cin>>tx>>ty>>kx>>ky;
  rep(i,Y)rep(j,X)cin>>wall[i][j];

  priority_queue<node>q;
  q.push(node(0,tx,ty,kx,ky));
  memset(vis,0,sizeof(vis));
  while(!q.empty()){
    int cc=q.top().cost;
    tx=q.top().tx;
    ty=q.top().ty;
    kx=q.top().kx;
    ky=q.top().ky;
    q.pop();
    if(cc>=100 || vis[tx][ty][kx][ky])continue;
    vis[tx][ty][kx][ky]=true;
    if(tx==kx && ty==ky){
      cout<<cc<<endl;
      return;
    }
    rep(i,4){
      int ntx=tx+dx[i],nty=ty+dy[i];
      int nkx=kx-dx[i],nky=ky-dy[i];

      if(0>ntx || ntx>=X ||
         0>nty || nty>=Y ||
         wall[nty][ntx])ntx=tx,nty=ty;
      if(0>nkx || nkx>=X ||
         0>nky || nky>=Y ||
         wall[nky][nkx])nkx=kx,nky=ky;
      if(vis[ntx][nty][nkx][nky])continue;
      q.push(node(cc+1,ntx,nty,nkx,nky));
    }
  }
  cout<<"NA"<<endl;
}

main(){
  while(cin>>X>>Y,X)
    solve();
}

C++: #include <bits/stdc++.h>
using namespace std;

int table[51][51];

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

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;

        tx--;ty--;kx--;ky--;

        for(int i=0;i<51;i++){
            for(int j=0;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=0;i<h;i++){
            for(int j=0;j<w;j++){
                //scanf(" %d",&table[i][j]);
                cin >> table[i][j];
            }
        }

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

            /*if(v[0] >= w || v[1] >= h || v[2] >= w || v[3] >= h || v[0] < 0 || v[1] < 0 || v[2] < 0 || v[3] < 0 || table[v[0]][v[1]] == 1 || table[v[2]][v[3]] == 1){
                continue;
            }*/

            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]++;

            vector<int> before(5);

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

            v[0]--; v[2]++;

            if(v[0] > 0 && v[2] < w && table[v[0]][v[1]] == 0 && table[v[2]][v[3]] == 0) {
                q.push(v);
            }

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

            v[0]++; v[2]--;

            if(v[2] > 0 && v[0] < w && table[v[0]][v[1]] == 0 && table[v[2]][v[3]] == 0) {
                q.push(v);
            }

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

            v[1]++; v[3]--;

            if(v[3] > 0 && v[1] < h && table[v[0]][v[1]] == 0 && table[v[2]][v[3]] == 0) {
                q.push(v);
            }

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

            v[1]--; v[3]++;

            if(v[1] > 0 && v[3] < h && table[v[0]][v[1]] == 0 && table[v[2]][v[3]] == 0) {
                q.push(v);
            }

            /*if(v[0] >= w || v[1] >= h || v[2] >= w || v[3] >= h || v[0] < 0 || v[1] < 0 || v[2] < 0 || v[3] < 0 || table[v[0]][v[1]] == 1 || table[v[2]][v[3]] == 1){

            }else {
                q.push(v);
            }*/



        }

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



    }

    return 0;
}