#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
template<class T> using V = vector<T>;
using VI = V<int>;
using VL = V<ll>;
using VS = V<string>;
template<class T> using PQ = priority_queue<T, V<T>, greater<T>>;
using graph = V<VI>;
template<class T> using w_graph = V<V<pair<int, T>>>;
#define FOR(i,a,n) for(int i=(a);i<(n);++i)
#define eFOR(i,a,n) for(int i=(a);i<=(n);++i)
#define rFOR(i,a,n) for(int i=(n)-1;i>=(a);--i)
#define erFOR(i,a,n) for(int i=(n);i>=(a);--i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define inside(h,w,y,x) (unsigned(y)<h&&unsigned(x)<w)
#ifdef _DEBUG
#define line cout << "-----------------------------\n"
#define stop system("pause")
#endif
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 61;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr int dy[]{ -1,0,1,0 }, dx[]{ 0,1,0,-1 };
template<class T> inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; }return false; }
inline void init() { cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); }
template<class T> inline istream& operator>>(istream& is, V<T>& v) { for (auto& a : v)is >> a; return is; }
template<class T, class U> inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template<class T> inline V<T> vec(size_t a) { return V<T>(a); }
template<class T> inline V<T> defvec(T def, size_t a) { return V<T>(a, def); }
template<class T, class... Ts> inline auto vec(size_t a, Ts... ts) { return V<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template<class T, class... Ts> inline auto defvec(T def, size_t a, Ts... ts) { return V<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }
template<class T> inline void print(const T& a) { cout << a << "\n"; }
template<class T, class... Ts> inline void print(const T& a, const Ts&... ts) { cout << a << " "; print(ts...); }
template<class T> inline void print(const V<T>& v) { for (int i = 0; i < v.size(); ++i)cout << v[i] << (i == v.size() - 1 ? "\n" : " "); }
template<class T> inline void print(const V<V<T>>& v) { for (auto& a : v)print(a); }
template<class T> inline constexpr const T& cumsum(const V<T>& a, int l, int r) { return 0 <= l && l <= r && r < a.size() ? a[r] - (l == 0 ? 0 : a[l - 1]) : 0; }//[l,r]
template<class T> inline constexpr const T& min(const V<T>& v) { return *min_element(all(v)); }
template<class T> inline constexpr const T& max(const V<T>& v) { return *max_element(all(v)); }

template<int M> class Indexer {
    static_assert(M > 0, "M must be positive");
    array<int, M> lim;
    int siz;
public:
    Indexer(initializer_list<int> lim_init) {
        assert(lim_init.size() == M);
        copy(all(lim_init), lim.begin());
        siz = 1;
        FOR(i, 0, M) {
            assert(lim[i] > 0);
            siz *= lim[i];
        }
    };
    int operator() (initializer_list<int> target_init) {
        assert(target_init.size() == M);
        array<int, M> target;
        copy(all(target_init), target.begin());
        int res = 0;
        FOR(i, 0, M)res = res * lim[i] + target[i];
        return res;
    }
    array<int, M> operator() (int a) {
        assert(a < size());
        array<int, M> res;
        rFOR(i, 0, M) {
            res[i] = a % lim[i];
            a /= lim[i];
        }
        return res;
    }
    int size() {
        return siz;
    }
};

int main() {
    init();

    int h, w; cin >> h >> w;
    int sy, sx, gy, gx; cin >> sy >> sx >> gy >> gx;
    --sy, --sx, --gy, --gx;
    VS s(h); cin >> s;

    auto dp = vec<bool>(h, w);
    dp[sy][sx] = true;
    queue<pair<int, int>> que;
    que.emplace(sy, sx);
    const int dy[4] = { -1,0,1,0 }, dx[4] = { 0,1,0,-1 };
    while (!que.empty()) {
        auto [y, x] = que.front();
        que.pop();
        FOR(i, 0, 4) {
            int ny = y + dy[i], nx = x + dx[i];
            if (!inside(h, w, ny, nx))continue;
            if (abs(s[y][x] - s[ny][nx]) > 1)continue;
            if (!dp[ny][nx]) {
                dp[ny][nx] = true;
                que.emplace(ny, nx);
            }
        }
        FOR(i, 0, 4) {
            int ny = y + dy[i], nx = x + dx[i];
            if (!inside(h, w, ny, nx))continue;
            if (s[y][x] <= s[ny][nx])continue;
            ny = y + dy[i] * 2, nx = x + dx[i] * 2;
            if (!inside(h, w, ny, nx))continue;
            if (s[y][x] != s[ny][nx])continue;
            if (!dp[ny][nx]) {
                dp[ny][nx] = true;
                que.emplace(ny, nx);
            }
        }
    }
    print(dp[gy][gx] ? "YES" : "NO");

    return 0;
}