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<vector>
#include<map>
#include<climits>
#include<set>
#include<queue>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cctype>
#include<string>
#include<bitset>
#include<cstring>
#include<list>
using namespace std;
typedef vector<string>vs;
typedef vector<int>vi;
typedef vector<vi>vvi;
typedef pair<int,int>pii;
typedef long long ll;
typedef pair<ll,ll>pll;
#define REP(i,x,n) for(int i=(x);i<(n);++i)
#define rep(i,x) REP(i,0,(x))
#define fi first
#define se second
#define each(i,c) for(typeof(c)::iterator i=(c).begin();i!=(c).end();++i)
#define all(c) (c).begin(),(c).end()
#define rall(c) (c).rbegin(),(c).rend()
#define pb push_back

const int dx[]={-1,0,1,0};
const int dy[]={0,-1,0,1};
int X,Y;
int stx,sty,skx,sky;
int fld[50][50];
bool f[50][50][50][50];

struct data{
    int tx,ty,kx,ky,cnt;
    data(int a,int b,int c,int d,int e):
        ty(a),tx(b),ky(c),kx(d),cnt(e){}
    data(){}
};
int solve(){
    fill_n(***f,50*50*50*50,false);
    queue<data>Q;Q.push(data(sty,stx,sky,skx,0));
    while(Q.size()){
        data d=Q.front();Q.pop();
        if(f[d.ty][d.tx][d.ky][d.kx])continue;
        f[d.ty][d.tx][d.ky][d.kx]=true;
        if(d.ty==d.ky&&d.tx==d.kx)return d.cnt;
        if(d.cnt>100)continue;
        rep(i,4){
            int nty=d.ty+dy[i];
            int ntx=d.tx+dx[i];
            int nky=d.ky+dy[(i+2)%4];
            int nkx=d.kx+dx[(i+2)%4];
            if(nty<0||nty>=Y||ntx<0||ntx>=X||fld[nty][ntx]){
                nty=d.ty;ntx=d.tx;
            }
            if(nky<0||nky>=Y||nkx<0||nkx>=X||fld[nky][nkx]){
                nky=d.ky;nkx=d.kx;
            }
            Q.push(data(nty,ntx,nky,nkx,d.cnt+1));
        }
    }
    return -1;
}

int main(){
    while(cin>>X>>Y,X||Y){
        cin>>stx>>sty;
        cin>>skx>>sky;
        stx--;sty--;skx--;sky--;
        rep(i,Y)rep(j,X)cin>>fld[i][j];
        int ans=solve();
        if(ans==-1)cout<<"NA"<<endl;
        else cout<<ans<<endl;
    }
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
#define pb push_back
typedef pair<int,int> P;
typedef pair<P,P> PP;
typedef pair<int,PP> PPP;
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};
int S[51][51][51][51];
int main()
{
	while(true){
		int X,Y;
		int tx;int ty;
		int kx;int ky;
		scanf("%d%d",&X,&Y);
		if(X==0&&Y==0)break;
		scanf("%d%d%d%d",&tx,&ty,&kx,&ky);tx--;ty--;kx--;ky--;
		int grid[51][51];
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				scanf("%d",&grid[i][j]);
			}
		}
		
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				for(int k=0;k<Y;k++){
					for(int l=0;l<X;l++){
						S[i][j][k][l]=1001;
					}
				}
			}
		}
		
		priority_queue<PPP>s;
		PP x;x.fi.sc=tx;x.fi.fi=ty;x.sc.sc=kx;x.sc.fi=ky;
		s.push(PPP(0,x));
		
		while(!s.empty()){
			PPP p=s.top();s.pop();
			if(S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]<=p.fi)continue;
			S[p.sc.fi.fi][p.sc.fi.sc][p.sc.sc.fi][p.sc.sc.sc]=p.fi;
			if(p.fi==100)continue;
			for(int k=0;k<4;k++){
				PP t;
				if(p.sc.fi.fi+dy[k]<0||p.sc.fi.fi+dy[k]>=Y||p.sc.fi.sc+dx[k]<0||p.sc.fi.sc+dx[k]>=X){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else if(grid[p.sc.fi.fi+dy[k]][p.sc.fi.sc+dx[k]]==1){
					t.fi.fi=p.sc.fi.fi;t.fi.sc=p.sc.fi.sc;
				}
				else{
					t.fi.sc=p.sc.fi.sc+dx[k];t.fi.fi=p.sc.fi.fi+dy[k];
				}
				if(p.sc.sc.fi-dy[k]<0||p.sc.sc.fi-dy[k]>=Y||p.sc.sc.sc-dx[k]<0||p.sc.sc.sc-dx[k]>=X){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else if(grid[p.sc.sc.fi-dy[k]][p.sc.sc.sc-dx[k]]==1){
					t.sc.sc=p.sc.sc.sc;t.sc.fi=p.sc.sc.fi;
				}
				else{
					t.sc.fi=p.sc.sc.fi-dy[k];t.sc.sc=p.sc.sc.sc-dx[k];
				}
				if(S[t.fi.fi][t.fi.sc][t.sc.fi][t.sc.sc]<=p.fi+1)continue;
				s.push(PPP(p.fi+1,t));
			}
		}
		int ans=1001;
		for(int i=0;i<Y;i++){
			for(int j=0;j<X;j++){
				ans=min(ans,S[i][j][i][j]);
				
			}
		}
		if(ans==1001)printf("NA\n");
		else printf("%d\n",ans);
	}
	return 0;
}