#include <bits/stdc++.h>
using namespace std;

int main() {
	int h, w;
	cin >> h >> w;

	int sy, sx, gy, gx;
	cin >> sy >> sx >> gy >> gx;
	sx--; sy--; gx--; gy--;

	vector<string> g(h);
	for (int i = 0; i < h; i++) cin >> g[i];

	static int dist[50][50];
	memset(dist, -1, sizeof(dist));
	dist[sy][sx] = 0;

	queue<pair<int, int>> q;
	q.emplace(sy, sx);

	while (!q.empty()) {
		int y, x;
		tie(y, x) = q.front(); q.pop();

		for (int i = 0; i < 4; i++) {
			int ny = y + (i - 2) % 2;
			int nx = x + (i - 1) % 2;
			if (ny < 0 || nx < 0 || ny >= h || nx >= w) continue;
			if (abs(g[ny][nx] - g[y][x]) <= 1 && dist[ny][nx] == -1) {
				dist[ny][nx] = dist[y][x] + 1;
				q.emplace(ny, nx);
			}
		}

		for (int i = 0; i < 4; i++) {
			int ny = y + (i - 2) % 2 * 2;
			int nx = x + (i - 1) % 2 * 2;
			if (ny < 0 || nx < 0 || ny >= h || nx >= w) continue;
			if (abs(g[ny][nx] - g[y][x]) == 0 && dist[ny][nx] == -1) {
				dist[ny][nx] = dist[y][x] + 1;
				q.emplace(ny, nx);
			}
		}
	}

	puts(dist[gy][gx] != -1 ? "YES" : "NO");
}