#include <iostream>
#include <queue>
#include <algorithm>
#include <cstring>
using namespace std;

#define MAX_Y 50
#define MAX_X 50

int X, Y;
bool F[MAX_Y][MAX_X];

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

const int dty[] = {0, 1, 0, -1},
          dtx[] = {1, 0, -1, 0},
          dky[] = {0, -1, 0, 1},
          dkx[] = {-1, 0, 1, 0};

bool used[MAX_Y][MAX_X][MAX_Y][MAX_X];
int bfs(int ty, int tx, int ky, int kx) {
    memset(used, 0, sizeof(used));
    queue<S> q;
    q.push(S(ty, tx, ky, kx, 0));
    while (!q.empty()) {
        S s = q.front(); q.pop();
        if (s.ty == s.ky && s.tx == s.kx) return s.t;
        if (s.t >= 100) break;
        for (int i = 0; i < 4; i++) {
            int nty = s.ty + dty[i],
                ntx = s.tx + dtx[i],
                nky = s.ky + dky[i],
                nkx = s.kx + dkx[i],
                nt  = s.t + 1;
            if (0 <= nty && nty < Y && 0 <= ntx && ntx < X) {
                if (F[nty][ntx]) {
                    nty = s.ty, ntx = s.tx;
                }
            } else {
                nty = s.ty, ntx = s.tx;
            }
            if (0 <= nky && nky < Y && 0 <= nkx && nkx < X) {
                if (F[nky][nkx]) {
                    nky = s.ky, nkx = s.kx;
                }
            } else {
                nky = s.ky, nkx = s.kx;
            }
            if (used[nty][ntx][nky][nkx]) continue;
            q.push(S(nty, ntx, nky, nkx, nt));
            used[nty][ntx][nky][nkx] = true;
        }
    }
    return -1;
}

int main() {
    while (cin >> X >> Y, X || Y) {
        int tx, ty, kx, ky;
        cin >> tx >> ty >> kx >> ky;
        ty--, tx--, ky--, kx--;
        for (int i = 0; i < Y; i++) {
            for (int j = 0; j < X; j++) {
                cin >> F[i][j];
            }
        }
        int t = bfs(ty, tx, ky, kx);
        if (t >= 0) {
            cout << t << endl;
        } else {
            cout << "NA" << endl;
        }
    }
    return 0;
}