HW = input().split()

H = int(HW[0])
W = int(HW[1])

tmp1 = ("." * W) + ".."
s = [list(tmp1)]
for i in range(H):
    tmp2 = "." + input() + "."
    s.append(list(tmp2))
s.append(list(tmp1))

checker = 1
for i in range(1, H+1):
    for j in range(1, W+1):
        if s[i, j] == "#":
            if s[i, j-1] == "." and s[i-1, j] == "." and s[i, j+1] == "." and s[i+1, j] == ".":
                checker == 0

if checker == 0:
    print("No")
else:
    print("Yes")
