#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

class union_find {
  public:
    union_find(int n) : data(n, -1) {}
    int unite(int x, int y) {
        x = root(x), y = root(y);
        if(x != y) {
            if(size(x) < size(y)) swap(x, y);
            data[x] += data[y];
            return data[y] = x;
        }
        return -1;
    }
    int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
    int size(int x) { return -data[root(x)]; }
    bool same(int x, int y) { return root(x) == root(y); }

  private:
    vector<int> data;
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int h,w; cin >> h >> w;
    int sx,sy,gx,gy; cin >> sx >> sy >> gx >> gy; sx--, sy--, gx--, gy--;
    auto hash = [&](int x, int y){ return x * w + y; };
    vector<string> b(h);
    rep(i,h) cin >> b[i];

    union_find uf(h * w);
    auto ok = [&](int x, int y){ return 0 <= x && x < h && 0 <= y && y < w; };
    int dx[] = {0, 1, 0, -1};
    int dy[] = {1, 0, -1, 0};
    rep(x,h)rep(y,w)rep(d,4) {
        int nx = x + dx[d], ny = y + dy[d];
        if(ok(nx, ny)) {
            if(abs(b[x][y] - b[nx][ny]) <= 1) uf.unite(hash(x, y), hash(nx, ny));
        }
        int mx = x + dx[d] * 2, my = y + dy[d] * 2;
        if(ok(mx, my)) {
            if(b[x][y] == b[mx][my] && b[x][y] > b[nx][ny]) uf.unite(hash(x, y), hash(mx, my));
        }
    }

    cout << (uf.same(hash(sx, sy), hash(gx, gy)) ? "YES" : "NO") << endl;
}