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

#define rep(i, j, n) for(int i=j;i<n;++i)
#define all(i) i.begin(),i.end()
#define rall(i) i.rbegin(),i.rend()
#define INF 1e9
const int mod = 1e9 + 7;

typedef long long i64;
typedef pair<int, int> pi;

template <class T> using vt = vector<T>;
template <class T> using vvt = vector<vector<T>>;

i64 gcd(i64 n, i64 m) {return (m == 0? n : gcd(m, n % m));}
i64 lcm(i64 n, i64 m) {return (n / gcd(n, m) * m);}
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int h, w;
  int sx, sy, gx, gy;
  cin >> h >> w >> sx >> sy >> gx >> gy;
  sx--; sy--; gx--; gy--;
  vt<string> b(h);
  rep(i, 0, h) cin >> b[i];

  vvt<bool> ok(h, vt<bool>(w, false));
  ok[sx][sy] = true;
  queue<pi> que;
  que.push({sx, sy});

  while(!que.empty()) {
    int x = que.front().first, y = que.front().second;
    que.pop();

    rep(i, 0, 4) {
      int nx = x + dx[i], ny = y + dy[i];
      if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
      if(ok[nx][ny]) continue;

      if(abs(b[x][y] - b[nx][ny]) <= 1) {
        que.push({nx, ny});
        ok[nx][ny] = true;
      }

      int nnx = nx + dx[i], nny = ny + dy[i];
      if(nnx < 0 || nnx >= h || nny < 0 || nny >= w) continue;
      if(ok[nnx][nny]) continue;

      if(b[x][y] == b[nnx][nny] && b[x][y] > b[nx][ny]) {
        que.push({nnx, nny});
        ok[nnx][nny] = true;
      }
    }
  }

  if(ok[gx][gy]) cout << "YES\n";
  else cout << "NO\n";
}