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 <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;

using T = tuple<int, int, int, int>;

const int INF = 1001001001;

int w, h;
bool grid[55][55];
int ti[55][55][55][55];
int dx[4] = { 0, 0, -1, 1 }, dy[4] = { -1, 1, 0, 0 };

bool f(int y, int x) {
    if (0 <= y && y < h && 0 <= x && x < w && !grid[y][x]) return true;
    return false;
}

int main() {
    while (cin >> w >> h && !(w == 0 && h == 0)) {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        tx--; ty--; kx--; ky--;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                cin >> grid[i][j];
            }
        }
        for (int i = 0; i < 55; i++) {
            for (int j = 0; j < 55; j++) {
                for (int k = 0; k < 55; k++) {
                    for (int l = 0; l < 55; l++) {
                        ti[i][j][k][l] = INF;
                    }
                }
            }
        }
        queue<T> que;
        que.push(T(ty, tx, ky, kx));
        ti[ty][tx][ky][kx] = 0;
        int gy, gx;
        bool flag = false;
        while (!flag && que.size()) {
            T t = que.front(); que.pop();
            int cty = get<0>(t), ctx = get<1>(t);
            int cky = get<2>(t), ckx = get<3>(t);
            for (int i = 0; i < 4; i++) {
                int nty = cty + dy[i], ntx = ctx + dx[i];
                if (!f(nty, ntx)) nty = cty, ntx = ctx;
                int nky = cky - dy[i], nkx = ckx - dx[i];
                if (!f(nky, nkx)) nky = cky, nkx = ckx;
                if (ti[nty][ntx][nky][nkx] <= ti[cty][ctx][cky][ckx] + 1) continue;
                ti[nty][ntx][nky][nkx] = ti[cty][ctx][cky][ckx] + 1;
                if (nty == nky && ntx == nkx) {
                    gy = nty, gx = ntx;
                    flag = true;
                    break;
                }
                que.push(T(nty, ntx, nky, nkx));
            }
        }
        int ans = ti[gy][gx][gy][gx];
        if (ans < 100) cout << ans << endl;
        else cout << "NA" << endl;
    }
}

C++: #include<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct oza{
	int x;
	int y;
};
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[50][50][50][50];
int main(){
	PP S;
	queue<PP> P;
	int  w,h,b;
	int d=0,c=0,i=0,j=0,l=-1,D[52][52];
	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=c;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;
		}
		S=P.back();
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
	
		S=P.front();
		c=S.Z;
		
		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(D[S.tx][S.ty]==1){
		S.tx=S.tx-tx[l];
		S.ty=S.ty-ty[l];
		}
		if(D[S.kx][S.ky]==1){
		S.kx=S.kx-kx[l];
		S.ky=S.ky-ky[l];
		}
		if(A[S.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		c=c+1;
		S.Z=c;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		
		
	}
	while(!P.empty()){
	P.pop();
	}
	c=0;
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

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

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

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

int main() {
	int X,Y;
	int tx,ty;
	int kx,ky;
	int d[50][50];
	int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
	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]);
			}
		}
		queue<S> q;
		map<P,bool> m;
		bool ok=false;
		S s={tx-1,ty-1,kx-1,ky-1,0};
		q.push(s);
		while(!q.empty()) {
			S s=q.front();q.pop();
			P p1(_P(s.tx,s.ty),_P(s.kx,s.ky));m[p1]=true;
			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];
				}
				P p2(_P(ntx,nty),_P(nkx,nky));
				if(m.find(p2)==m.end()) {
					S ns={ntx,nty,nkx,nky,s.turn+1};
					q.push(ns);
				}
			}
		}
		if(!ok) printf("NA\n");
	}
}