#pragma GCC target("avx2")
#pragma GCC optimize("03")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std; typedef long double ld; typedef long long ll;
typedef unsigned long long ull;
#define endl "\n"
#define FOR(i,a,b) for(int i=(a);i<=(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define ALL(x) (x).begin(), (x).end()
constexpr int INF=1<<30; constexpr ll LINF=1LL<<60; constexpr ll mod=1e9+7; constexpr int NIL = -1;
template<class T>vector<T> vec(int len, T elem) { return vector<T>(len, elem); } // auto dp = vec(52, vec(103, vec(103, INF)));
template<class T>inline bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
template<class T>inline int popcount(T a) {return __builtin_popcount(a);}
template<class T>inline T emod(T a, T p) { return (a%p + p) % p;}
//-------------------
vector<vector<bool>> visited(55, vector<bool>(55, false));

int h, w;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

void bfs(int y, int x, vector<string> &B) {
    queue<PII> q;
    q.push({y, x});
    auto onfield = [&](int yy, int xx) {
        bool ans = true;
        if(0 > yy or yy >= h) ans = false;
        if(0 > xx or xx >= w) ans = false;
        // cout << (ans? "Y":"N") << endl;
        return ans;
    };
    while(!q.empty()) {
        auto [y, x] = q.front(); q.pop();
        // cout << y << " " << x << endl;
        if(!visited[y][x]) {
            // cout << "OK";
            visited[y][x] = true;
            rep(i, 4) {
                int ny = y + dy[i];
                int nx = x + dx[i];
                // cout <<ny << nx << endl;
                if(onfield(ny, nx) and abs((int) B[y][x] - B[ny][nx]) <= 1) {
                    q.push({ny, nx});
                }
            }
            rep(i, 4) {
                int ny = y + dy[i] * 2;
                int nx = x + dx[i] * 2;
                if(onfield(ny, nx) and B[y][x] == B[ny][nx] and B[y][x] - B[y+dy[i]][x+dx[i]] > 0) {
                    q.push({ny, nx});
                }
            }
        }
    }
}
int main() {
    cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(15);
    cin >> h >> w;
    int s[2];
    int g[2];
    cin >> s[0] >> s[1] >> g[0] >> g[1];
    s[0]--; s[1]--; g[0]--; g[1]--;
    vector<string> B(h);
    rep(i, h) cin >> B[i];

    bfs(s[0], s[1], B);

    // rep(i, h) rep(j, w) cout << (visited[i][j]? 1:0 )<< endl;

    if(visited[g[0]][g[1]]) cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}