h, w = (list)(map(int, input().split()))
l = [[lin for lin in input()] for _ in range(h)]

gri = [[0 for i in range(w+2)] for _ in range(h+2)]
for i in range(h+2):
    for j in range(w+2):
        if i == 0 or i == h+1 or j == 0 or j == w+1:
            gri[i][j] = '.'
        else:
            gri[i][j] = l[i-1][j-1]

flag = 0
for i in range(1, h+1):
    for j in range(1, w+1):
        if gri[i][j] == '#':
            flag = 0
            if gri[i-1][j] == '.' and gri[i+1][j] == '.' and gri[i][j-1] == '.' and gri[i][j+1] == '.':
                print("No")
                exit(1)

if flag == 0:
    print("No")
else:
    print("Yes")
# print(l)
# print(gri)
