#include <bits/stdc++.h>

using namespace std;

struct Initializer {
  Initializer() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(15);
  }
} initializer;

template<int N> class AdjacentLoop {
private:
  static int dy(int i);
  static int dx(int i);

  struct Iterator {
    const int y, x, h, w;
    int val;

    Iterator(int y, int x, int h, int w, int val) : y(y), x(x), h(h), w(w), val(val) {
      for (; this->val < N; ++this->val) {
        int yy = y + dy(this->val);
        int xx = x + dx(this->val);
        if (0 <= yy && yy < h && 0 <= xx && xx < w) break;
      }
    }

    pair<int, int> operator*() {return make_pair(y + dy(val), x + dx(val));}

    bool operator!=(Iterator& itr) {return val < itr.val;}

    void operator++() {
      while (++val < N) {
        int yy = y + dy(val);
        int xx = x + dx(val);
        if (0 <= yy && yy < h && 0 <= xx && xx < w) break;
      }
    }
  };

  Iterator i, n;

public:
  AdjacentLoop(int y, int x, int h, int w) : i(y, x, h, w, 0), n(y, x, h, w, N) {}

  Iterator& begin() {return i;}

  Iterator& end() {return n;}
};

template<> int AdjacentLoop<2>::dy(int i) {
  constexpr int dy[]{0, 1};
  return dy[i];
}

template<> int AdjacentLoop<2>::dx(int i) {
  constexpr int dx[]{1, 0};
  return dx[i];
}

template<> int AdjacentLoop<4>::dy(int i) {
  constexpr int dy[]{0, -1, 0, 1};
  return dy[i];
}

template<> int AdjacentLoop<4>::dx(int i) {
  constexpr int dx[]{1, 0, -1, 0};
  return dx[i];
}

template<> int AdjacentLoop<5>::dy(int i) {
  constexpr int dy[]{0, -1, 0, 1, 0};
  return dy[i];
}

template<> int AdjacentLoop<5>::dx(int i) {
  constexpr int dx[]{1, 0, -1, 0, 0};
  return dx[i];
}

template<> int AdjacentLoop<8>::dy(int i) {
  constexpr int dy[]{-1, -1, -1, 0, 0, 1, 1, 1};
  return dy[i];
}

template<> int AdjacentLoop<8>::dx(int i) {
  constexpr int dx[]{-1, 0, 1, -1, 1, -1, 0, 1};
  return dx[i];
}

template<> int AdjacentLoop<9>::dy(int i) {
  constexpr int dy[]{-1, -1, -1, 0, 0, 0, 1, 1, 1};
  return dy[i];
}

template<> int AdjacentLoop<9>::dx(int i) {
  constexpr int dx[]{-1, 0, 1, -1, 0, 1, -1, 0, 1};
  return dx[i];
}

template<typename T> inline istream& operator>>(istream &s, vector<T> &v) {
  for (T &t : v) s >> t;
  return s;
}

template<typename T> inline ostream& operator<<(ostream &s, const vector<T> &v) {
  for (const T &t : v) s << t << endl;
  return s;
}

template<typename T> inline T min(vector<T>& v) {return *min_element(v.begin(), v.end());}

template<typename T> inline T max(vector<T>& v) {return *max_element(v.begin(), v.end());}

template<typename T> inline int min_element(vector<T>& v) {return min_element(v.begin(), v.end()) - v.begin();}

template<typename T> inline int max_element(vector<T>& v) {return max_element(v.begin(), v.end()) - v.begin();}

template<typename T> inline void sort(vector<T>& v) {sort(v.begin(), v.end());}

template<typename T, typename Function> inline void sort(vector<T>& v, Function func) {sort(v.begin(), v.end(), func);}

template<typename T> inline void rsort(vector<T>& v) {sort(v.rbegin(), v.rend());}

template<typename T> inline void reverse(vector<T>& v) {reverse(v.begin(), v.end());}

template<typename T> inline void unique(vector<T>& v) {v.erase(unique(v.begin(), v.end()), v.end());}

template<typename T> inline void nth_element(vector<T>& v, int n) {nth_element(v.begin(), v.begin() + n, v.end());}

template<typename T> inline bool next_permutation(vector<T>& v) {return next_permutation(v.begin(), v.end());}

template<typename T> inline int find(vector<T>& v, T t) {return find(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline int in(vector<T> v, T t) {return find(v, t) != (int)v.size();}

template<typename T> inline int lower_bound(vector<T>& v, T t) {return lower_bound(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline int upper_bound(vector<T>& v, T t) {return upper_bound(v.begin(), v.end(), t) - v.begin();}

template<typename T> inline T accumulate(const vector<T>& v, function<T(T, T)> func = plus<T>()) {return accumulate(v.begin(), v.end(), T(), func);}

template<typename T> inline void adjacent_difference(vector<T>& v) {adjacent_difference(v.begin(), v.end(), v.begin());}

template<typename T> inline void adjacent_difference(vector<T>& v, vector<T>& u) {adjacent_difference(v.begin(), v.end(), u.begin());}

template<typename T> inline void partial_sum(vector<T>& v, vector<T>& u) {partial_sum(v.begin(), v.end(), u.begin());}

template<typename T> inline T inner_product(vector<T>& v, vector<T>& u) {return inner_product(v.begin(), v.end(), u.begin(), T(0));}

template<typename T> inline int count(const vector<T>& v, T t) {return count(v.begin(), v.end(), t);}

template<typename T, typename Function> inline int count_if(const vector<T>& v, Function func) {return count_if(v.begin(), v.end(), func);}

template<typename T, typename Function> inline void remove_if(vector<T>& v, Function func) {v.erase(remove_if(v.begin(), v.end(), func), v.end());}

template<typename T, typename Function> inline bool any_of(vector<T> v, Function func) {return any_of(v.begin(), v.end(), func);}

template<typename T> inline vector<T> subvector(vector<T>& v, int a, int b) {return vector<T>(v.begin() + a, v.begin() + b);}

template<typename T> inline int kinds(const vector<T>& v) {return set<T>(v.begin(), v.end()).size();}

template<typename T> inline void iota(vector<T>& v) {iota(v.begin(), v.end(), T());}

template<typename T> inline bool is_sorted(const vector<T>& v) {return is_sorted(v.begin(), v.end());}

class UnionFind {
private:
  int n;
  vector<int> a;
public:
  UnionFind(int n) : n(n), a(n, -1) {}
  int find(int x) {return a[x] < 0 ? x : (a[x] = find(a[x]));}
  bool equal(int x, int y) {return find(x) == find(y);}
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if (x == y) return;
    if (a[x] > a[y]) swap(x, y);
    a[x] += a[y];
    a[y] = x;
    --n;
  }
  int size() {return n;}
  int size(int x) {return -a[find(x)];}
};

int main() {
  int h, w, sx, sy, gx, gy;
  cin >> h >> w >> sx >> sy >> gx >> gy;
  --sx, --sy, --gx, --gy;
  vector<string> b(h);
  cin >> b;
  UnionFind uf(h * w);
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      for (auto k : AdjacentLoop<2>(i, j, h, w)) {
        int ii = k.first, jj = k.second;
        if (abs(b[i][j] - b[ii][jj]) <= 1) uf.unite(i * w + j, ii * w + jj);
      }
      if (j < w - 2 && b[i][j] > b[i][j + 1] && b[i][j] == b[i][j + 2]) uf.unite(i * w + j, i * w + j + 2);
      if (i < h - 2 && b[i][j] > b[i + 1][j] && b[i][j] == b[i + 2][j]) uf.unite(i * w + j, (i + 2) * w + j);
    }
  }
  cout << (uf.equal(sx * w + sy, gx * w + gy) ? "YES" : "NO") << endl;
}