from itertools import product
n, m = map(int,input().split())
canvas = []
for i in range(n):
    canvas.append(input())
for i,j in product([num for num in range(n)],[num for num in range(m)]):
    if canvas[i][j] == '.':
        continue
    result = 0
    if i > 0 and canvas[i-1][j] == '#':
        result += 1
    if i < n-1 and canvas[i+1][j] == '#':
        result += 1
    if j > 0 and canvas[i][j-1] == '#':
        result += 1
    if j < m-1 and canvas[i][j+1] == '#':
        result += 1
    if result == 0:
        flag = True
        break
if flag:
    print('No')
else:
    print('Yes')
        
            