h, w = map(int, input().split())
ans = "Yes"
c = [0]*(w+2)
s = c
for i in range(h):
    S = ["0"]
    S1 = list(input())
    S.append(S1)
    S.append("0")
    s.append(S)
s.append(c)

for i in range(1,h+1):
    for j in range(1, w+1):
        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)