h,w = map(int,input().split())
flag = 0
for i in range(h):
  s = input()
  for j in range(w):
    if s[j] == "#":
      if j != w-1:
        if s[j+1] == "#":
          flag += 1
if flag == 0:
  print("No")
else:
  print("Yes")