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

struct UnionFind{
    vector<int> data;
    int __size;
    UnionFind(int sz) {
    data.assign(sz, -1);
    __size = sz;
  }
 
  bool unite(int x, int y) {
    x = find(x), y = find(y);
    if(x == y) return (false);
    if(data[x] > data[y]) swap(x, y);//親は負でサイズを保存
    __size--;
    data[x] += data[y];
    data[y] = x;
    return (true);
  }
 
  int find(int k) {
    if(data[k] < 0) return (k);
    return (data[k] = find(data[k]));
  }

  bool same(int x, int y){
      return find(x) == find(y);
  }
 
  int size(int k) {
    return (-data[find(k)]);
  }

  int unum() {
    return (__size);
  }
};
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
int main(){
  int h, w;
  cin >> h >> w;
  int sx, sy, gx, gy;
  cin >> sx >> sy >> gx >> gy;
  sx--; sy--; gx--; gy--;
  UnionFind uf(h*w);
  vector<string> g(h);
  rep(i,h) cin >> g[i];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {

      for (int d = 1; d <= 2; d++) {
        for (int k = 0; k < 4; k++) {
          int x = i + d * dx[k], y = j + d * dy[k];
          if (x < 0 || y < 0 || x >= h || y >= w) continue;
          if (d == 2 && g[i][j] == g[x][y] && g[i][j] >= g[i+dx[k]][j+dy[k]]) {
            uf.unite(i*w+j, x*w+y);
          }
          if (d == 1 && abs(g[i][j] - g[x][y]) <= 1) {
            uf.unite(i*w+j, x*w+y);
          }
        }
      }
    }
  }
  if (uf.same(sx*w+sy, gx*w+gy)) cout << "YES" << endl;
  else cout << "NO" << endl;
  return 0;
}