h, w = map(int, input().split())
s = [['.']*(w+2)]
s = s + [['.']+list(input())+[','] for _ in range(w)]
s = s + [['.']*(w+2)]
for i in range(1, w+1):
    for j in range(1, w+1):
        if s[i][j] == '#':
           up = s[i-1][j]
           left = s[i][j-1]
           right = s[i][j+1]
           down = s[i+1][j]
           if up == '.' and left == '.' and right == '.' and down == '.':
               print('No')
               exit()
print('Yes')
