#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

# %%
H, W = map(int, readline().split())
H += 4
W += 4
sx, sy, gx, gy = map(lambda x: int(x) + 1, readline().split())
INF = 20
A = [INF] * (H * W)
for h in range(2, H - 2):
    A[h * W + 2:(h + 1) * W - 2] = map(int, readline().decode().rstrip())

# %%
N = H * W
graph = [[] for _ in range(N)]
s = sx * W + sy
g = gx * W + gy


# %%
for i in range(2, H - 2):
    for j in range(2, W - 2):
        v = i * W + j
        for dx in (1, -1, W, -W):
            if A[v] - A[v + dx] in (-1, 0, 1):
                graph[v].append(v + dx)
            if A[v] == A[v + dx + dx] and A[v] > A[v + dx]:
                graph[v].append(v + dx + dx)

# %%
visited = [False] * N
visited[s] = True
stack = [s]
while stack:
    v = stack.pop()
    for w in graph[v]:
        if visited[w]:
            continue
        stack.append(w)
        visited[w] = True


# %%
answer = 'YES' if visited[g] else 'NO'
print(answer)