h, w = map(int, input().split())
s = [input() for i in range(h)]
for i in range(h):
    for j in range(w):
        ans = "No"
        if s[i][j]=="#":
            for x, y in [(-1, 0), (0, -1), (0, 1), (1, 0)]:
                if  0<=i+x<h and 0<=j+y<w and s[i+x][j+y]=="#":
                    ans = "Yes"
            if ans == "No":
                print(ans)
                exit()
print(ans)