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 := 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 <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

int dp[52][52][52][52];
void solve(int h, int w){
    for(auto &i : dp) for(auto &j : i) for(auto &k : j) for(auto &l : k) l = INF<int>;
    int tx, ty, kx, ky;
    cin >> tx >> ty >> kx >> ky;
    vector<vector<int>> G(h+2, vector<int>(w+2, 1));
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            cin >> G[i+1][j+1];
        }
    }
    array<int, 4> dx{-1, 1, 0, 0}, dy{0, 0, -1, 1};
    queue<tuple<int, int, int, int>> Q;
    Q.emplace(ty, tx, ky, kx);
    dp[ty][tx][ky][kx] = 0;
    while(!Q.empty()){
        int y1, x1, y2, x2; tie(y1, x1, y2, x2) = Q.front(); Q.pop();
        if(dp[y1][x1][y2][x2] >= 100) break;
        if(y1 == y2 && x1 == x2){
            cout << dp[y1][x1][y2][x2] << "\n";
            return;
        }
        for (int k = 0; k < 4; ++k) {
            int Y1 = y1+dy[k], X1 = x1+dx[k], Y2 = y2-dy[k], X2 = x2-dx[k];
            if(G[Y1][X1]) Y1 -= dy[k], X1 -= dx[k];
            if(G[Y2][X2]) Y2 += dy[k], X2 += dx[k];
            if(dp[Y1][X1][Y2][X2] > dp[y1][x1][y2][x2]+1){
                Q.emplace(Y1, X1, Y2, X2);
                dp[Y1][X1][Y2][X2] = dp[y1][x1][y2][x2]+1;
            }
        }
    }
    puts("NA");
}

int main() {
    int w, h;
    while(cin >> w >> h, w){
        solve(h, w);
    }
    return 0;
}

C++: #include <iostream>
#include <queue>
#include <map>

#define MAX_X 1000
#define MAX_Y 1000

using namespace std;

typedef pair<int,int> P;
typedef pair<P,P> PP;

int d[MAX_Y][MAX_X][MAX_Y][MAX_X];

int tx,ty,kx,ky,ntx,nty,nkx,nky;
int ans;

short maze[MAX_Y][MAX_X];
int Y,X;

int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};

bool bfs(){
	queue<PP> que;
	map<PP,int> mat;
	que.push(make_pair(make_pair(ty,tx),make_pair(ky,kx)));
	
	mat[que.front()]=0;
	while (que.size()) {
		PP p=que.front();
		que.pop();
		if (p.first.first==p.second.first&&p.first.second==p.second.second) {
			ans=d[p.first.first][p.first.second][p.second.first][p.second.second];
			return true;
		}
		if (d[p.first.first][p.first.second][p.second.first][p.second.second]>=100) {
			return false;
		}
		if (mat[que.front()]) {
			continue;
		}
		for (int i=0; i<4; i++) {
			ntx=p.first.second+dx[i],nty=p.first.first+dy[i],nkx=p.second.second+dx[i]*(-1),nky=p.second.first+dy[i]*(-1);
			int flag=2;
			if (!(0<=ntx&&ntx<X&&0<=nty&&nty<Y&&maze[nty][ntx]!=1)){
				flag-=1;
				ntx=p.first.second;
				nty=p.first.first;
			}
			if (!(0<=nkx&&nkx<X&&0<=nky&&nky<Y&&maze[nky][nkx]!=1)) {
				flag-=1;
				nkx=p.second.second;
				nky=p.second.first;
			}
			if (flag!=0) {
				que.push(make_pair(make_pair(nty,ntx),make_pair(nky,nkx)));
				d[nty][ntx][nky][nkx]=d[p.first.first][p.first.second][p.second.first][p.second.second]+1;
			}
			mat[que.front()] = d[nty][ntx][nky][nkx];
		}
	}
	return false;
}

int main(){
	while (cin>>X>>Y&&X&&Y) {
		cin>>tx>>ty>>kx>>ky;
		tx-=1;
		ty-=1;
		kx-=1;
		ky-=1;
		for (int i=0; i<Y; i++) {
			for (int j=0; j<X; j++) {
				cin>>maze[i][j];
			}
		}
		if(bfs()){
			cout << ans <<endl;
		}
		else {
			cout << "NA" << endl;
		}
	}
}

C++: #include <cstdio>
#include <cstring>
#include <queue>
using namespace std;

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

S::S(int _tx,int _ty,int _kx,int _ky,int _turn) {
	tx=_tx;
	ty=_ty;
	kx=_kx;
	ky=_ky;
	turn=_turn;
}

bool d[50][50];
bool vst[50][50][50][50];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	while(scanf("%d %d",&X,&Y),X||Y) {
		scanf("%d %d",&tx,&ty);
		scanf("%d %d",&kx,&ky);
		for(int j=0;j<Y;j++) {
			for(int i=0;i<X;i++) {
				scanf("%d",&d[i][j]);
			}
		}
		tx--;ty--;kx--;ky--;
		queue<S> q;
		bool ok=false;
		q.push(S(tx,ty,kx,ky,0));
		memset(vst,false,sizeof(vst));
		vst[tx][ty][kx][ky]=true;
		while(!q.empty()) {
			S s=q.front();q.pop();
			if(s.turn>=100) break;
			if(s.tx==s.kx&&s.ty==s.ky) {
				printf("%d\n",s.turn);
				ok=true;
				break;
			}
			for(int i=0;i<4;i++) {
				int ntx=s.tx+dx[i],nty=s.ty+dy[i];
				int nkx=s.kx-dx[i],nky=s.ky-dy[i];
				if(0>ntx||ntx>=X||0>nty||nty>=Y||d[ntx][nty]) {
					ntx-=dx[i],nty-=dy[i];
				}
				if(0>nkx||nkx>=X||0>nky||nky>=Y||d[nkx][nky]) {
					nkx+=dx[i],nky+=dy[i];
				}
				if(!vst[ntx][nty][nkx][nky]) {
					vst[ntx][nty][nkx][nky]=true;
					q.push(S(ntx,nty,nkx,nky,s.turn+1));
				}
			}
		}
		if(!ok) printf("NA\n");
	}
	return 0;
}