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

// 基本テンプレート
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define mat(type, c, m, n) vector<vector<type>> c(m, vector<type>(n));for(auto& r:c)for(auto& i:r)cin>>i;
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a); i>n; --i)
#define each(x,y) for(auto &(x):(y))
#define perm(c) sort(all(c));for(bool c##p=1;c##p;c##p=next_permutation(all(c)))
#define cauto const auto&
#define UNIQUE(v) v.erase( unique(all(v)), v.end() );
#define len(x) ((int)(x).size())
#define length(a)   (sizeof(a)/sizeof(a[0]))
inline void print() {cout << endl;}
template <class H, class... T> inline void print(H h, T... t){cout << h << " ";print(t...);}
#define dbg(v) for(auto i : v) cout << i << " "; cout << endl;

// 型
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;

ll mod = (int)1e9 + 7;

// 定数
#define PI acos(-1.0)
//constexpr int EPS = (1e-9);
//constexpr int INF = 100000000;

// 4近傍
constexpr int dx[] = {1, 0, -1, 0};
constexpr int dy[] = {0, 1, 0, -1};

inline bool bfs() {
	int h, w; cin >> h >> w;
	int sx, sy, gx, gy; cin >> sx >> sy >> gx >> gy;
	--sx, --sy, --gx, --gy;
	string s[60]; rep(i, 0, h) cin >> s[i];
	deque<pair<int, int>> q;
	q.push_back(make_pair(sx, sy));
	vector<vb> d(h, vb(w, false));
	d[sx][sy] = true;
	while(!q.empty()) {
		int x, y; tie(x, y) = q.front(); q.pop_front();
		if(y == gy && x == gx) return true;
		rep(i, 0, 4) {
			int nx = x + dx[i];
			int ny = y + dy[i];
			if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
			if(abs(s[nx][ny] - s[x][y]) <= 1 && !d[nx][ny]){
				q.push_back(make_pair(nx,ny));
				d[nx][ny] = true;
			}
			nx += dx[i]; ny += dy[i];
			if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
			if(s[nx][ny] == s[x][y] && !d[nx][ny]){
				q.push_back(make_pair(nx,ny));
				d[nx][ny] = true;
			}
		}
	}
	return false;
}

int main() {
//	cout << setprecision(12) << fixed;

	P(bfs() ? "YES" : "NO");

	return 0;
}