h,w = map(int,input().split())
s = [input() for _ in range(w)]
l = []
for i in range(1,h-1):
    for j in range(1,w-1):
        if s[i][j] == "#":
            if s[i+1][j] == "#" or s[i-1][j] == "#" or s[i][j+1] == "#" or s[i][j-1] == "#":
                l.append(0)
            else:
                l.append(1)

if sum(l) == 0:
    print("Yes")
else:
    print("No")