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 v, ok := memo[now.Person]; ok && v <= now.Turn {
			continue
		}
		if ans<=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<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<queue>
#include<iostream>
using namespace std;
struct data{
    int x;
    int y;
    int u;
    int v;
    int t;
};

bool vis[60][60][60][60] = {};
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
int main(void){
    int w,h;
    while(cin>>w>>h,w){
        int x,y,u,v;
        cin>>x>>y>>u>>v;
        x--,y--,u--,v--;
        bool screen[60][60] = {};
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cin>>screen[i][j];
            }
        }
        data D;
        D.x = x,D.y = y;
        D.u = u,D.v = v;
        D.t = 0;
        queue<data> Q;
        Q.push(D);

        while(!Q.empty()){
            data E = Q.front();Q.pop();

            if(E.x == E.u&&E.y == E.v){
                cout<<E.t<<endl;
                goto e;
            }
            if(E.t>99)break;
            for(int i = 0;i < 4;i++){

                    data F = E;
                    F.t++;
                    F.x+=dx[i],F.y+=dy[i],F.u+=dx[(i+2)%4],F.v+=dy[(i+2)%4];
                    if(!(0<=F.x&&F.x<w&&0<=F.y&&F.y<h)){
                        F.x = E.x,F.y = E.y;
                    }
                    if(screen[F.x][F.y])F.x = E.x,F.y = E.y;
                    if(!(0<=F.u&&F.u<w&&0<=F.v&&F.v<h)){
                        F.u = E.u,F.v = E.v;
                    }
                    if(screen[F.u][F.v])F.u = E.u,F.v = E.v;
                    if(vis[F.x][F.y][F.u][F.v]||vis[F.u][F.v][F.x][F.y])continue;

                    vis[F.x][F.y][F.u][F.v] = true;
                    vis[F.u][F.v][F.x][F.y] = true;
                    Q.push(F);

            }

        }
        cout<<"NA"<<endl;
        e:;
    }


    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();
			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)));
				}
			}
		}
		int MIN = 100;
		for (int i = 0; i < b; i++) {
			for (int j = 0; j < c; j++) {
				MIN = min(MIN, a[i][j][i][j]);
			}
		}
		if (MIN == 100)puts("NA");
		else cout << MIN << endl;
	}
}

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>
using namespace std;
static const double EPS = 1e-5;
typedef long long ll;
typedef pair<int,int> pi;
#define rep(i,n) for(int i=0;i<n;i++)
#define mp make_pair


int dx[]={0,-1,0,1};
int dy[]={-1,0,1,0};
bool v[50][50][50][50];
int f[50][50];
int x,y;
int tx,ty,kx,ky;


main(){
	while(cin>>x>>y,x){
		cin>>tx>>ty>>kx>>ky;
		--tx;--ty;--kx;--ky;
		rep(i,y)rep(j,x)cin>>f[j][i];
		memset(v,0,sizeof(v));

		v[tx][ty][kx][ky]=1;
		queue<pair<pair<pi,pi>,int> > Q;
		Q.push(mp(mp(mp(tx,ty),mp(kx,ky)),0));
		
		while(!Q.empty()){
			tx=Q.front().first.first.first;
			ty=Q.front().first.first.second;
			kx=Q.front().first.second.first;
			ky=Q.front().first.second.second;
			int time=Q.front().second;Q.pop();
			
			
			rep(d,4){
				int ntx=tx+dx[d],nty=ty+dy[d];
				int nkx=kx-dx[d],nky=ky-dy[d];
				
				if(ntx<0 || ntx>=x || nty<0 || nty>=y || f[ntx][nty])ntx=tx,nty=ty;
				if(nkx<0 || nkx>=x || nky<0 || nky>=y || f[nkx][nky])nkx=kx,nky=ky;
				if(v[ntx][nty][nkx][nky] || time>=99)continue;
				if(ntx==nkx && nty==nky){
					cout<<time+1<<endl;
					goto END;
				}
				
				Q.push(mp(mp(mp(ntx,nty),mp(nkx,nky)),time+1));
				v[ntx][nty][nkx][nky]=1;
			}
		}
		
		puts("NA");END:;
	}
}