#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b) - 1;i>=(a);i--)
#define REP(i,n) for(int i=0;i<(n);i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)

#define PB push_back
#define INF INT_MAX/3
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define CLR(a) memset(a,0,sizeof(a))

typedef long long int ll;

using namespace std;
int dx[] = {-1,0,0,1};
int dy[] = {0,1,-1,0};
int xs,ys,tx,ty,kx,ky;


int main(){
    while(true){
	cin >> xs >> ys;
	if(xs == 0 && ys == 0) break;
	cin >> tx >> ty;
	cin >> kx >> ky;
	tx--;
	ty--;
	kx--;
	ky--;
	if(tx==kx&&ty==ky){
	    cout << 0 << endl;
	    continue;
	}
	vector< vector<int> > map(ys,vector<int>(xs));
	REP(i,ys)REP(j,xs) cin >> map[i][j];

	queue<int> qtx;
	queue<int> qty;
	queue<int> qkx;
	queue<int> qky;
	queue<int> qn;
	set< pair< pair<int,int> , pair<int,int> > > used;
	int ans = 100;
	qtx.push(tx);
	qty.push(ty);
	qkx.push(kx);
	qky.push(ky);
	qn.push(1);
	while(!qtx.empty()){
	    int x1 = qtx.front();
	    int y1 = qty.front();
	    int x2 = qkx.front();
	    int y2 = qky.front();
	    int n = qn.front();
	    if(n >= 100){
		ans = min(ans,100);
		break;
	    }
	    qtx.pop();
	    qty.pop();
	    qkx.pop();
	    qky.pop();
	    qn.pop();
	    REP(i,4){
		int ntx = x1 + dx[i];
		int nty = y1 + dy[i];
		int nkx = x2 - dx[i];
		int nky = y2 - dy[i];
		if(ntx<0 || xs <= ntx) ntx = x1;
		if(nty<0 || ys <= nty) nty = y1;
		if(nkx<0 || xs <= nkx) nkx = x2;
		if(nky<0 || ys <= nky) nky = y2;
		if(map[nty][ntx] == 1) {
		    ntx = x1;
		    nty = y1;
		}
		if(map[nky][nkx] == 1) {
		    nkx = x2;
		    nky = y2;
		}
		pair< pair<int,int> , pair<int,int> > pp(pair<int,int>(ntx,nty),pair<int,int>(nkx,nky));
		if(used.find(pp) != used.end()) continue;
		used.insert(pp);

		if(ntx==nkx&&nty==nky){
		    ans = min(ans,n);
		    break;
		}
		qtx.push(ntx);
		qty.push(nty);
		qkx.push(nkx);
		qky.push(nky);
		qn.push(n+1);
	    }
	    if(ans < 100) break;
	}
	if(ans>=100) cout << "NA" << endl;
	else cout << ans << endl;
    }
    return 0;
}