h,w=map(int,input().split())
s=[input() for i in range(h)]

c=0
for i in range(h):
  for j in range(w):
    if s[i][j]=='#':
      for x,y in [1,0],[-1,0],[0,1],[0,-1]:
        ny=i+y
        nx=j+x
        if 0<=ny<=h-1 and 0<=nx<=w-1:
          if s[ny][nx]=='#':
            c=1
print('Yes' if c==1 else 'No')