#96
h, w = map(int, input().split())
s = [['.']*(w+2)] + [['.']+list(input())+['.'] for _ in range(w)] + [['.']*(w+2)]
a = True
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 == '.':
                a = False
                break
    if not a:
        break
if a ==True:
    print('Yes')
else:
    print('No')