H,W = map(int,input().split())
L = []
for i in range(H):
    l = list(input())
    L.append(l)

def judge(list,i,j):
    if i != 0:
        top = list[i-1][j]
    else:
        top = "."
    if j != 0:
        left = list[i][j-1]
    else:
        left = "."
    if i != W-1:
        bottom = list[i+1][j]
    else:
        bottom = "."
    if j != H-1:
        right = list[i][j+1]
    else:
        right = "."
    return top == "#" or left == "#" or bottom == "#" or right == "#"

for i in range(W):
    for j in range(H):
        if L[i][i] == "#" and judge(L,i,j) is False:
            print("No")
            exit()
print("Yes")