h, w = map(int, input().split())

temp = "0" * (h+2)

s = [temp]

for i in range(h):
    s.append("0" + input() + "0")

s.append(temp)

# print(s)

for i in range(h+2):
    for j in range(w+2):
        flag = False
        if s[i][j] == "#":
            if s[i-1][j] == "#" or s[i+1][j] == "#" or s[i][j+1] == "#" or s[i][j-1] == "#":
                flag = True
            if not flag:
                print("No")
                exit()

print("Yes")