H,W=map(int,input().split())
s = [['.' for i in range(H+2)] for j in range(W+2)]
f=0
for i in range(H):
 s[i+1] = ['.'] + list(input()) + ['.']
for i in range(H+2):
 if f == 0:
  for j in range(W+2):
   if s[i][j] == '#':
    if s[i-1][j] == '.' and s[i+1][j] == '.' and s[i][j-1] == '.' and s[i][j+1] == '.':
     f = 1
     print('No')
     break
if f == 0:
 print('Yes')