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<stdio.h>
#include<iostream>
#include<queue>
#include<string.h>
using namespace std;
struct PP{
	int kx;
	int ky;
	int tx;
	int ty;
	int Z;
};
int A[52][52][52][52];
int main(){
	PP S;
	queue<PP> P;
	int  w,h;
	int d=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=0;
	P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			d=-1;
			printf("%d\n",S.Z);
		}
	while(d!=-1){
		l++;
		if(l==4){
		l=0;
		S=P.front();
		P.pop();
		if(P.empty()){
			printf("NA\n");
		break;
		}
		}
		S=P.front();
		
		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(A[S.tx][S.ty][S.kx][S.ky]==1){
			continue;
		}
		A[S.tx][S.ty][S.kx][S.ky]=1;

		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];
		}
		S.Z++;
		P.push(S);
		if(S.tx==S.kx&&S.ty==S.ky){
			printf("%d\n",S.Z);
			break;
		}	
		if(S.Z==100){
			printf("NA\n");
		break;
		}
	
		
	}
	while(!P.empty()){
	P.pop();
	}
	l=-1;
	scanf("%d %d",&w,&h);
	}	
	return 0;

}

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

int dx[4] = { -1,0,0,1 }, dy[4] = { 0,-1,1,0 };
int main() {
	int a, b;
	while (cin >> a >> b, a | b) {
		int c, d, e, f;
		cin >> c >> d >> e >> f;
		c--; d--; e--; f--;
		bool ba[50][50];
		int k[50][50];
		memset(k, -1, sizeof(k));
		for (int g = 0; g < a; g++) {
			for (int h = 0; h < b; h++) {
				cin >> ba[g][h];
			}
		}
		if ((((c - e) & 1) == 0) && (((d - f) & 1) == 0)) {
			queue<P>Q;
			if(!ba[c][d]&&!ba[e][f]) Q.push(P(c, d));
			k[c][d] = 0;
			while (Q.size()) {
				P o = Q.front(); Q.pop();
				for (int i = 0; i < 4; i++) {
					int x = dx[i],y=dy[i];
						if (o.first + x >= 0 && o.first + x < a&&o.second + y >= 0 && o.second + y < b) {
							if (c + e - (o.first + x) >= 0 && c + e - (o.first + x) < a&&d + f - (o.second + y) >= 0 && d + f - (o.second + y) < b) {
								if (!ba[o.first + x][o.second + y] && !ba[c + e - (o.first + x)][d + f - (o.second + y)] && k[o.first + x][o.second + y] == -1) {
									Q.push(P(o.first + x, o.second + y));
									k[o.first + x][o.second + y] = k[o.first][o.second] + 1;
								}
							}
						}
				}
			}
			if (k[(c + e) / 2][(d + f) / 2] == -1)puts("NA");
			else cout << k[(c + e) / 2][(d + f) / 2] << endl;
		}
		else puts("NA");
	}
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <math.h>
#include <vector>
#include <queue>
#include <algorithm>
#include <sstream>
#include <string>
using namespace std;
#define FOR(I,N) for(int I = 0; I < (int)(N); I++)
#define FIN(V) cout<<V<<endl
#define pb push_back
#define INF (1 << 30)
typedef pair<int, int> P;

int solve();
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int w, h, tx, ty, kx, ky;
int maps[51][51];
int memo[51][51][51][51];


struct Data{
    P pt, pk;
    int cnt;
    Data(P pt_, P pk_, int cnt_){
        pt = pt_;
        pk = pk_;
        cnt = cnt_;
    }
    Data(){}
};

int main(void){
    while(cin >> w >> h, w){
        cin >> tx >> ty;
        cin >> kx >> ky;
        fill_n(*maps, 51*51, 1);
        FOR(i, h)FOR(j, w){
            cin >> maps[i+1][j+1];
        }
        int a = solve();
        if(a == -1 || a >= 100)FIN("NA");
        else FIN(a);
    }
    return 0;    
}


int solve(){
    int ans = -1;
    fill_n(***memo, 51*51*51*51, INF);
    queue<Data> que;
    que.push(Data(P(tx,ty), P(kx, ky), 0));
    while(que.size()){
        Data data = que.front();
        que.pop();
        int x1 = data.pt.first;
        int y1 = data.pt.second;
        int x2 = data.pk.first;
        int y2 = data.pk.second;
        int cost = data.cnt;
        if(cost > 100)break;
        if(memo[x1][y1][x2][y2] <= cost)continue;
        memo[x1][y1][x2][y2] = cost;
        if(x1 == x2 && y1 == y2){ans = cost;break;};
        FOR(i, 4){
            int nx1 = x1 + dx[i];
            int ny1 = y1 + dy[i];
            int nx2 = x2 - dx[i];
            int ny2 = y2 - dy[i];
            if(maps[ny1][nx1] == 1){nx1 = x1;ny1 = y1;};
            if(maps[ny2][nx2] == 1){nx2 = x2;ny2 = y2;};
            que.push(Data(P(nx1,ny1), P(nx2, ny2), cost+1));
        }
    }

    return ans;
}