h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
r = False
for i in range(h):
  for j in range(w):
    if s[i][j] == ".":
      continue
    elif 0 < (i - 1) and s[i - 1][j] == "#":
      r = True
      continue
    elif (i + 1) < h and s[i + 1][j] == "#":
      r = True
      continue
    elif 0 < (j - 1) and s[i][j - 1] == "#":
      r = True
      continue
    elif (j + 1) < w and s[i][j + 1] == "#":
      r = True
      continue
    else:
      r = False

print("Yes") if r else print("No")
