import pprint

h, w = map(int, input().split())
sx, sy, gx, gy = map(int, input().split())
sx -= 1
sy -= 1
gx -= 1
gy -= 1

B = []
for i in range(h):
    B.append(list(map(int, list(input()))))

seen = [[False for _ in range(w)] for _ in range(h)]

dx = [-1, 1, 0, 0]
dy = [0, 0, -1, 1]
dx2 = [-2, 2, 0, 0]
dy2 = [0, 0, -2, 2]

def dfs(x, y):
    if x == gx and y == gy:
        return True

    seen[x][y] = True

    for i in range(4):
        nx = x + dx[i]
        ny = y + dy[i]
        if nx < 0 or nx >= h or ny < 0 or ny >= w:
            continue
        if seen[nx][ny] or abs(B[x][y] - B[nx][ny]) > 1:
            continue
        if dfs(nx, ny):
            return True

    for i in range(4):
        nx = x + dx2[i]
        ny = y + dy2[i]
        if nx < 0 or nx >= h or ny < 0 or ny >= w:
            continue
        if seen[nx][ny] or B[x][y] != B[nx][ny]:
            continue
        if dfs(nx, ny):
            return True
    return False

if dfs(sx, sy):
    print("YES")
else:
    print("NO")

#pprint.pprint(seen)