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++: //1.includes
#include<iostream>
#include<queue>
#include<tuple>
#include<algorithm>
using namespace std;
//2.defines
#define MAX_N 60
#define INF 1000000000
//3.variables
int dp[MAX_N][MAX_N][MAX_N][MAX_N];
int H, W, A1, A2, B1, B2;
int x[MAX_N][MAX_N];
queue<tuple<int, int, int, int>>Q;
//4.functions
int solve() {
	dp[A1][A2][B1][B2] = 0;
	Q.push(make_tuple(A1, A2, B1, B2));
	while (!Q.empty()) {
		tuple<int, int, int, int>tup = Q.front();
		Q.pop();
		int a1 = get<0>(tup);
		int a2 = get<1>(tup);
		int a3 = get<2>(tup);
		int a4 = get<3>(tup);
		int dx[4] = { 1,0,-1,0 };
		int dy[4] = { 0,-1,0,1 };
		for (int i = 0; i < 4; i++) {
			int cx = a1 + dx[4], cy = a2 + dy[4];
			int ex = a3 - dx[4], ey = a4 - dy[4];
			if (x[cx][cy] == 1) { cx = a1; cy = a2; }
			if (x[ex][ey] == 1) { ex = a3; ey = a4; }
			if (dp[cx][cy][ex][ey] == INF) {
				dp[cx][cy][ex][ey] = dp[a1][a2][a3][a4] + 1;
			}
		}
	}
	int minx = INF;
	for (int i = 1; i <= H; i++) {
		for (int j = 1; j <= W; j++) {
			minx = min(minx, dp[i][j][i][j]);
		}
	}
	return minx;
}
void _memset() {
	for (int i = 0; i < MAX_N; i++) {
		for (int j = 0; j < MAX_N; j++) {
			for (int k = 0; k < MAX_N; k++) {
				for (int l = 0; l < MAX_N; l++) {
					dp[i][j][k][l] = INF;
				}
			}
		}
	}
	for (int i = 0; i < MAX_N; i++) {
		for (int j = 0; j < MAX_N; j++) {
			x[i][j] = 0;
		}
	}
}
int main() {
	while (true) {
		_memset();
		cin >> H >> W;
		if (H == 0 && W == 0) { break; }
		cin >> A1 >> A2 >> B1 >> B2;
		for (int i = 1; i <= H; i++) {
			for (int j = 1; j <= W; j++) {
				cin >> x[i][j];
			}
		}
		int v = solve();
		if (v >= 100) { cout << "NA" << endl; }
		else { cout << v << endl; }
	}
	return 0;
}

C++: #include<cstdio>
#include<iostream>
#include<queue>
#include<string.h>
#include<cstring>
void saka();
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int w,h;
PP S;
int A[52][52][52][52],D[52][52];
int main(){
	queue<PP> P;
	int d=0,i=0,j=0,l=-1;
	int tx[4]={ 1, 0,-1,0 };       
	int kx[4]={-1, 0, 1,0 };
	int ty[4]={ 0, 1, 0,-1 };
	int ky[4]={ 0, -1, 0,1};
	scanf("%d %d",&w,&h);
	while(w!=0||h!=0){
	memset(A,0,sizeof(A));
		for(i=0;i<=h+1;i++){
		for(j=0;j<=w+1;j++){
		D[i][j]=1;
		}
	}

	scanf("%d %d",&S.tx,&S.ty);
	scanf("%d %d",&S.kx,&S.ky);
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
		scanf("%d",&D[i][j]);
		}
	}
	S.Z=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			printf("%d\n",S.Z);
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		S.tx=S.tx+tx[l];
		S.ty=S.ty+ty[l];
		S.kx=S.kx+kx[l];
		S.ky=S.ky+ky[l];
		if(A[S.ty][S.tx][S.ky][S.kx]==1){
			continue;
		}
		A[S.ty][S.tx][S.ky][S.kx]=1;
		if(D[S.ty][S.tx]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.ky][S.kx]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		//saka();
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==99){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	d=0;
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}
void saka()
{
	int i,j;
	for(i=1;i<=h;i++){
		for(j=1;j<=w;j++){
			if(S.kx==j&&S.ky==i){
				printf("k");
			}
			else if(S.tx==j&&S.ty==i){
				printf("t");
			}
			else printf("%d",D[i][j]);
		}
		printf("\n");
	}
	printf("\n");



}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
#include <stack>
#include <queue>
#include <cstring>
#include <list>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> VI;
static const double EPS = 1e-5;
static const int INFTY = (1<<21);
static const ll LLINFTY = (1LL<<53);
#define REP(i,m,n) for(i=m;i<n;i++)
#define rep(i,n) REP(i,0,n)
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin();i!=(c).end();++i)
#define out(a,b) (a<0||a>=b)
struct node{
  int tx,ty;
  int kx,ky;
  int c;
  int mini;
  node(){}
  node(int a,int b,int c_,int d,int e):tx(a),ty(b),kx(c_),ky(d),c(e),
  mini((abs(a-c_)+abs(b-d))/2){}
  bool operator>(const node& e)const{
    return c+mini>e.c+e.mini;
  }
};
bool used[50][50][50][50];
int dx[]={0,1,0,-1};
int dy[]={0,-1,0,1};
int main(void)
{
  int w,h,i,j,ii,jj;
  int tx,ty,kx,ky;
  int g[50][50];
  node p;
  for(;;){
    scanf("%d%d",&w,&h); if(!w)break;
    scanf("%d%d%d%d",&tx,&ty,&kx,&ky); tx--; ty--; kx--; ky--;
    rep(i,h)rep(j,w){
      scanf("%d",g[i]+j);
      rep(ii,h)rep(jj,w)used[i][j][ii][jj]=false;
    }
    priority_queue<node,vector<node>,greater<node> >q;
    q.push( node(tx,ty,kx,ky,0) );
    used[ty][tx][ky][kx]=true;
    while( !q.empty() ){
      p=q.top(); q.pop();
      if(p.tx==p.kx && p.ty==p.ky){
        printf("%d\n",p.c);
        goto END;
      }
      rep(i,4){
        tx=p.tx+dx[i]; ty=p.ty+dx[3-i];
        kx=p.kx+dy[i]; ky=p.ky+dy[3-i];
        if(out(tx,w)||out(ty,h)||g[ty][tx])tx=p.tx,ty=p.ty;
        if(out(kx,w)||out(ky,h)||g[ky][kx])kx=p.kx,ky=p.ky;
        if(!used[ty][tx][ky][kx]){
          used[ty][tx][ky][kx]=true;
          q.push(node(tx,ty,kx,ky,p.c+1));
        }
      }
    }
    puts("NA");
  END:;
  }
}