from collections import deque

D = [(1, 0), (0, 1), (-1, 0), (0, -1)]
DD = [(2, 0), (0, 2), (-2, 0), (0, -2)]

h, w = map(int, input().split())
si, sj, gi, gj = map(int, input().split())
si -= 1
sj -= 1
gi -= 1
gj -= 1
B = [list(map(int, list(input()))) for _ in range(h)]

visited = [[False for _ in range(w)] for _ in range(h)]
visited[si][sj] = True
Que = deque([(si, sj)])
while Que:
    ci, cj = Que.popleft()
    if ci == gi and cj == gj:
        print("YES")
        exit()
    for di, dj in D:
        ni = ci + di
        nj = cj + dj
        if 0 <= ni < h and 0 <= nj < w and not visited[ni][nj]:
            if abs(B[ci][cj] - B[ni][nj]) <= 1:
                visited[ni][nj] = True
                Que.append((ni, nj))
    for di, dj in DD:
        ni = ci + di
        nj = cj + dj
        if 0 <= ni < h and 0 <= nj < w and not visited[ni][nj]:
            mi = (ci + ni) // 2
            mj = (cj + nj) // 2
            if B[ci][cj] == B[ni][nj] and B[ci][cj] > B[mi][mj]:
                visited[ni][nj] = True
                Que.append((ni, nj))
print("NO")