H, W = map(int, input().split())
l = [["." for i in range(W + 2)]]
for i in range(H):
    temp = list(input())
    temp.insert(0, ".")
    temp.append(".")
    l.append(temp)

l.append(["." for i in range(W + 2)])
Flag = True
for i in range(H + 2):
    if i == 0 or i == H + 1:
        continue
    
    for j in range(W + 2):
        if j == 0 or j == W + 1:
            continue
        if l[i][j] == "#":
            #上下左右
            if l[i-1][j] == "#" or l[i+1][j] == "#" or l[i][j-1] == "#" or l[i][j+1] == "#":
                Flag == False
                break
    
    if Flag == False:
        break 

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