H, W = map(int, input().split())
s = [list(input()) for _ in range(H)]

s.insert(0, ['.']*W)
s.append(['.']*W)
for i in range(W+2):
    s[i].insert(0, '.')
    s[i].append('.')
#print(s)

flag = False
for i in range(1, H+1):
    for j in range(1, W+1):
        if s[i][j] == '#':
            if s[i][j-1] == s[i][j+1] == s[i-1][j] == s[i+1][j] == '.':
                print('No')
                flag = True
                break
    if flag:
        break
else:
    print('Yes')