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 ans <= now.Turn {
			continue
		}
		if _, ok := memo[now.Person]; ok {
			continue
		}
		memo[now.Person] = now.Turn

		if now.Person.Distance() == 0 && ans > now.Turn {
			ans = 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<ctime>
#include<cmath>
#include<cstring>
#include<cctype>
#include<complex>
#include<iostream>
#include<sstream>
#include<algorithm>
#include<functional>
#include<vector>
#include<string>
#include<stack>
#include<queue>
#include<map>
#include<set>
using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
const int Dx[] = {-1,0,1,0},Dy[] = {0,-1,0,1};
#define INF 1e+8
#define EPS 1e-8
#define rep(i,j) for(int i = 0; i < (j); i++)
#define reps(i,j,k) for(int i = (j); i < (k); i++)
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> Pii;
int X,Y;
int l,m,n,o;
bool vis[52][52][52][52];
class P{
	public:
	int ax,ay,bx,by;
	int cnt;
	P(int ax,int ay,int bx,int by,int cnt):ax(ax),ay(ay),bx(bx),by(by),cnt(cnt){}
};
bool c(int stage[52][52],int f,int i){
	if(f == 0){
		if(o+Dy[i] >= 0 && o+Dy[i] <= Y && n+Dx[i] >= 0 && n+Dx[i] <= X &&
			m+dy[i] >= 0 && m+dy[i] <= Y && l+dx[i] >= 0 && l+dx[i] <= X)return true;
		else return false;
	}
	if(f == 1){
		if(m+dy[i] >= 0 && m+dy[i] <= Y && l+dx[i] >= 0 && l+dx[i] <= X)return true;
		else return false;
	}
	if(f == 2){
		if(o+Dy[i] >= 0 && o+Dy[i] <= Y && n+Dx[i] >= 0 && n+Dx[i] <= X)return true;
		else return false;
	}
}
int main(){
	while(scanf("%d%d",&X,&Y),(X|Y)){
		int tx,ty;
		scanf("%d%d",&tx,&ty);
		int kx,ky;
		scanf("%d%d",&kx,&ky);
		int stage[52][52];
		rep(i,Y)rep(j,X)scanf("%d",&stage[i][j]);
		int check = -1;
		queue<P> Q;
		Q.push(P(tx-1,ty-1,kx-1,ky-1,0));
		X--;Y--;
		memset(vis,false,sizeof(vis));
		while( Q.size() ){
			P p = Q.front();Q.pop();
			if(p.cnt == 100)break;
			if(p.ax == p.bx && p.ay == p.by){check=p.cnt;break;}
			l = p.ax;m = p.ay;n = p.bx,o = p.by;
			//printf("D:%d %d %d %d\n",l,m,n,o);
			rep(i,4){
				if(stage[m+dy[i]][l+dx[i]] == 0 && c(stage,1,i) && !vis[l+dx[i]][m+dy[i]][n][o] &&
					(stage[o+Dy[i]][n+Dx[i]] == 1 || o+Dy[i] < 0 || o+Dy[i] > Y || n+Dx[i] < 0 || n+Dx[i] > X) ){
					Q.push(P(l+dx[i],m+dy[i],n,o,p.cnt+1));
					vis[l+dx[i]][m+dy[i]][n][o] = true;
				}
				else if(stage[o+Dy[i]][n+Dx[i]] == 0 && c(stage,2,i) && !vis[l][m][n+Dx[i]][o+Dy[i]] &&
					(stage[m+dy[i]][l+dx[i]] == 1 || m+dy[i] < 0 || m+dy[i] > Y || l+dx[i] < 0 || l+dx[i] > X) ){
					Q.push(P(l,m,n+Dx[i],o+Dy[i],p.cnt+1));
					vis[l][m][n+Dx[i]][o+Dy[i]] = true;
				}
				else if(c(stage,0,i) && stage[m+dy[i]][l+dx[i]] == 0 && stage[o+Dy[i]][n+Dx[i]] == 0 && !vis[l+dx[i]][m+dy[i]][n+Dx[i]][o+Dy[i]]){
					Q.push(P(l+dx[i],m+dy[i],n+Dx[i],o+Dy[i],p.cnt+1));
					vis[l+dx[i]][m+dy[i]][n+Dx[i]][o+Dy[i]] = true;
				}
			}
		}
		(check != -1) ? printf("%d\n",check) : puts("NA");
	}
	return 0;
}

C++: #include<bits/stdc++.h>
#define p pair<int,int>
#define P pair<p,p>
using namespace std;

int a[50][50][50][50];
int x[4] = { -1,0,0,1 }, y[4] = { 0,-1,1,0 };
int S[50][50];
signed main() {
	int b, c;
	while (cin >> c >> b, b | c) {
		memset(a, 0x3f, sizeof(a));
		int d, e, f, g; cin >> e >> d >> g >> f; d--; e--; f--; g--;
		a[d][e][f][g] = 0;
		for (int i = 0; i < b; i++) {
			for (int j = 0; j < c; j++) {
				scanf("%d", &S[i][j]);
			}
		}
		queue<P>Q;
		Q.push(P(p(d,e),p(f,g)));
		while (Q.size()) {
			P t = Q.front(); Q.pop();
			if (a[t.first.first][t.first.second][t.second.first][t.second.second] >= 100)break;
			if (t.first.first == t.second.first&&t.first.second == t.second.second) {
				cout << a[t.first.first][t.first.second][t.second.first][t.second.second] << endl;
				goto l;
		}
			for (int i = 0; i < 4; i++) {
				int j = 3 - i;
				p n, m; n = t.first; m = t.second;
				n.first += x[i]; n.second += y[i];
				m.first += x[j]; m.second += y[j];
				if (n.first < 0 || n.first >= b || n.second < 0 || n.second >= c||S[n.first][n.second]==1) {
					n.first -= x[i]; n.second -= y[i];
				}
				if (m.first < 0 || m.first >= b || m.second < 0 || m.second >= c||S[m.first][m.second]==1) {
					m.first -= x[j]; m.second -= y[j];
				}
				if (a[n.first][n.second][m.first][m.second] == 1061109567) {
					a[n.first][n.second][m.first][m.second] = a[t.first.first][t.first.second][t.second.first][t.second.second]+1;
					Q.push(P(p(n.first,n.second),p(m.first,m.second)));
				}
			}
		}
		puts("NA");
	l:;
	}
}