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(102)
	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 _, 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 += 1
			if next.Turn <= 100 {
				//heap.Push(&pq, next)
				//pq.Push(next)
				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 <iostream>
#include <fstream>
#include <algorithm>
#include <cassert>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

#define INF 1e9
#define rep(i,n) for(int i=0;i<n;i++)

struct C{
	int tx,ty,kx,ky;
	C(int tx,int ty,int kx,int ky):
	tx(tx),ty(ty),kx(kx),ky(ky) {}
};

int X,Y,tx,ty,kx,ky,m[51][51],dx[]={1,0,-1,0},dy[]={0,1,0,-1},d[51][51][51][51];

int bfs(int tx,int ty,int kx,int ky){
	queue<C> q;
	rep(i,Y)rep(j,X)rep(k,Y)rep(l,X)d[i][j][k][l]=INF;
	q.push(C(tx,ty,kx,ky));
	d[tx][ty][kx][ky]=0;
	while(!q.empty()){
		C c=q.front();q.pop();
		if(d[c.tx][c.ty][c.kx][c.ky]==100)return -1;
		if(c.tx==c.kx&&c.ty==c.ky)return d[c.tx][c.ty][c.kx][c.ky];
		rep(i,4){
			int ntx=c.tx+dx[i],nty=c.ty+dy[i],nkx=c.kx-dx[i],nky=c.ky-dy[i];
			if(ntx<0||ntx>=X||nty<0||nty>=Y||m[nty][ntx]){ntx=c.tx;nty=c.ty;}
			if(nkx<0||nkx>=X||nky<0||nky>=Y||m[nky][nkx]){nkx=c.kx;nky=c.ky;}
			if(d[ntx][nty][nkx][nky]==INF){
				q.push(C(ntx,nty,nkx,nky));
				d[ntx][nty][nkx][nky]=d[c.tx][c.ty][c.kx][c.ky]+1;
			}
		}
	}
	return -1;
}

int main(){
	while(cin>>X>>Y&&X){
		cin>>tx>>ty>>kx>>ky;
		tx--;ty--;kx--;ky--;
		rep(i,Y)rep(j,X)cin>>m[i][j];
		int ans=bfs(tx,ty,kx,ky);
		if(ans>=0)cout<<ans<<endl;
		else cout<<"NA"<<endl;
	}
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
struct Data{
	int x1,y1,x2,y2,cnt;
	Data(){}
	Data(int x1,int y1,int x2,int y2,int cnt):
		x1(x1),y1(y1),x2(x2),y2(y2),cnt(cnt){}
};
bool memo[50][50][50][50];
int dx[] = {0,1,-1,0}, dy[] = {1,0,0,-1};
int main() {
	int x,y;
	while(scanf("%d%d",&x,&y),(x|y)) {
		int tx,ty;
		int kx,ky;
		scanf("%d%d",&tx,&ty);
		scanf("%d%d",&kx,&ky);
		tx--;ty--;kx--;ky--;
		int stage[51][51];
		for(int i = 0; i < y; i++) {
			for(int j = 0; j < x; j++) {
				scanf("%d",&stage[i][j]);
			}
		}
		queue<Data> Q;
		Q.push(Data(tx,ty,kx,ky,0));
		int ans = -1;
		while(!Q.empty()) {
			Data d = Q.front();Q.pop();
			if(d.cnt >= 100) break;
			if(d.x1 == d.x2 && d.y1 == d.y2) {
				ans = d.cnt;
				break;
			}
			if(memo[d.x1][d.y1][d.x2][d.y2]) continue;
			memo[d.x1][d.y1][d.x2][d.y2] = true;
			for(int i = 0; i < 4; i++) {
				bool flg1 = false,flg2 = false;
				int nx1 = dx[i] + d.x1, ny1 = dy[i] + d.y1;
				int nx2 = dx[3-i] + d.x2, ny2 = dy[3-i] + d.y2;
				if(nx1 < 0 || nx1 >= x || ny1 < 0 || ny1 >= y || stage[ny1][nx1] == 1) flg1 = true;
				if(nx2 < 0 || nx2 >= x || ny2 < 0 || ny2 >= y || stage[ny2][nx2] == 1) flg2 = true;
				if(!(flg1 | flg2)) {
					Q.push(Data(nx1,ny1,nx2,ny2,d.cnt + 1));
				}
				if(!flg1 && flg2) {
					Q.push(Data(nx1,ny1,d.x2,d.y2,d.cnt+1));
				}
				if(flg1 && !flg2) {
					Q.push(Data(d.x1,d.y1,nx2,ny2,d.cnt+1));
				}
			}
		}
		if(ans == -1) puts("NA");
		else printf("%d\n",ans);
	}
	return 0;
}