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

s = [0 for i in range(h)]
for i in range(h):
    s[i] = list(input())


flag = False


def hantei(i, j):
    if i < 0 or i > h-1 or j < 0 or j > w-1:
        return False
    elif s[i][j] == "#":
        return True
    else:
        return False


def hantei2(i,j):
    if hantei(i-1, j) or hantei(i+1, j) or hantei(i, j-1) or hantei(i, j+1):
        return True
    else:
        return  False


for i in range(0, h):
    if flag == False:
        break
    for j in range(0, w):
        if s[i][j] == '#':
            flag = hantei2(i,j)
            if flag == False:
                break
            
        

if flag:
    print("Yes")
else:
    print("No")



