h, w = map(int, input().split())
ans = "Yes"
s = []
for i in range(h):
    S = list(input())
    s.append(S)

for i in range(h):
    for j in range(w):
        if s[i][j]=="#":
            if s[i-1][j]!="#" and s[i+1][j]!="#" and s[i][j-1]!="#" and s[i][j+1]!="#":
                ans ="No"
            else:
                continue
print(ans)