#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())
#define endl "\n"

struct UnionFind {
    UnionFind() {}
    UnionFind(int n) {
        resize(n);
    }
    
    void resize(int n) {
        par.resize(n, -1);
    }
    
    int root(int x) {
        if (par[x] < 0) return x;
        return par[x] = root(par[x]);
    }
    
    bool merge(int x, int y) {
        int rx = root(x);
        int ry = root(y);
        if (rx == ry) return false;
        if (par[rx] > par[ry]) swap(rx, ry);
        par[rx] += par[ry];
        par[ry] = rx;
        return true;
    }
    
    bool is_same(int x, int y) {
        return (root(x) == root(y));
    }
    
    int size(int x) {
        return -par[root(x)];
    }
    
private:
    vector<int> par;
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    const ll d[2][2] = {{0, 1}, {1, 0}};
    const ll ds[2][2] = {{0, 2}, {2, 0}};
    ll h, w;
    cin >> h >> w;
    ll sy, sx, gy, gx;
    cin >> sy >> sx >> gy >> gx;
    sx--; sy--; gx--; gy--;
    vector<string> b(h);
    rep(i, h) cin >> b[i];
    UnionFind uf(h * w);
    rep(y, h) {
        rep(x, w) {
            {
                rep(i, 2) {
                    ll nx = x + d[i][0];
                    ll ny = y + d[i][1];
                    if ((nx >= w) || (ny >= h)) continue;
                    ll dh = abs(b[y][x] - b[ny][nx]);
                    if (dh > 1) continue;
                    uf.merge(y * w + x, ny * w + nx);
                }
            }
            {
                rep(i, 2) {
                    ll nx = x + ds[i][0];
                    ll ny = y + ds[i][1];
                    if ((nx >= w) || (ny >= h)) continue;
                    ll dh = abs(b[y][x] - b[ny][nx]);
                    if (dh >= 1) continue;
                    ll mx = (x + nx) / 2;
                    ll my = (y + ny) / 2;
                    if (b[y][x] <= b[my][mx]) continue;
                    uf.merge(y * w + x, ny * w + nx);
                }
            }
        }
    }
    cout << ((uf.root(sy * w + sx) == uf.root(gy * w + gx)) ? "YES" : "NO") << endl;
    return 0;
}