#include <algorithm>
#include <iostream>
#include <vector>
#include <queue>
#include <tuple>
using namespace std;

int dij[] = {0, 1, 0, -1, 0};
int main() {
    int h, w; cin >> h >> w;
    int si, sj, gi, gj;
    cin >> si >> sj >> gi >> gj; si--, sj--, gi--, gj--;
    vector<string> s(h);
    for (string &si: s) cin >> si;
    vector<vector<int>> visited(h, vector<int>(w, false));
    queue<pair<int, int>> que;
    visited[si][sj] = true; que.emplace(si, sj);
    while (!que.empty()) {
        int i, j;
        tie(i, j) = que.front(); que.pop();
        for (int k = 0; k < 4; k++) {       // はしごを縦に使う
            int ni = i + dij[k];
            int nj = j + dij[k + 1];
            if (ni < 0 || ni >= h || nj < 0 || nj >= w) continue;
            if (visited[ni][nj]) continue;
            if (abs(s[i][j] - s[ni][nj]) > 1) continue;
            visited[ni][nj] = true;
            que.emplace(ni, nj);
        }
        for (int k = 0; k < 4; k++) {       // はしごを横に使う
            int ni = i + dij[k] * 2;
            int nj = j + dij[k + 1] * 2;
            if (ni < 0 || ni >= h || nj < 0 || nj >= w) continue;
            if (visited[ni][nj]) continue;
            if (s[i][j] != s[ni][nj]) continue;
            if (s[i][j] <= s[i + dij[k]][j + dij[k + 1]]) continue;
            visited[ni][nj] = true;
            que.emplace(ni, nj);
        }
    }
    cout << (visited[gi][gj] ? "YES" : "NO") << endl;
    return 0;
}