#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<60;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int h, w;
int sx, sy, gx, gy;
string maps[50];

bool done[50][50];

int main() {
	cin >> h >> w;
	cin >> sy >> sx >> gy >> gx;
	sx--; sy--; gx--; gy--;
	
	REP(i, h) cin >> maps[i];
	
	queue<pii> que;
	que.push(pii(sx, sy));
	
	while (!que.empty()) {
		int x = que.front().first;
		int y = que.front().second;
		
		que.pop();
		
		if (done[y][x]) continue;
		
		done[y][x] = true;
		
		int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
		
		REP(t, 2) {
			REP(i, 4) {
				int nx = x + dx[i] * (t + 1);
				int ny = y + dy[i] * (t + 1);
				
				if (!(nx >= 0 && nx < w && ny >= 0 && ny < h)) continue;
				if (done[ny][nx]) continue;
				
				if (t == 0) {
					if (abs(maps[y][x] - maps[ny][nx]) > 1) continue;
				}
				else {
					if (maps[y][x] != maps[ny][nx] || maps[y + dy[i]][x + dx[i]] > maps[y][x]) continue;
				}
				
				que.push(pii(nx, ny));
			}
		}
		
	}
	
	puts(done[gy][gx] ? "YES" : "NO");
	
	return 0;
}