#include <atcoder/dsu>
#include <cmath>
#include <iostream>
#include <vector>

int main() {
    using namespace std;
    int h, w, sx, sy, gx, gy;
    cin >> h >> w >> sx >> sy >> gx >> gy;
    int s = (sx - 1) * w + (sy - 1);
    int g = (gx - 1) * w + (gy - 1);
    vector<string> b(h);
    for (auto &e : b) { cin >> e; }

    atcoder::dsu uf(h * w);
    for (int x = 0; x < h; x++) {
        for (int y = 0; y < w; y++) {
            int p = x * w + y;
            if (x < h - 1 && abs(b[x][y] - b[x + 1][y]) < 2) {
                uf.merge(p, p + w);
            }
            if (y < w - 1 && abs(b[x][y] - b[x][y + 1]) < 2) {
                uf.merge(p, p + 1);
            }
            if (x < h - 2 && b[x][y] == b[x + 2][y] && b[x][y] > b[x + 1][y]) {
                uf.merge(p, p + w * 2);
            }
            if (y < w - 2 && b[x][y] == b[x][y + 2] && b[x][y] > b[x][y + 1]) {
                uf.merge(p, p + 2);
            }
        }
    }
    cout << (uf.same(s, g) ? "YES\n" : "NO\n");
}