h, w = map(int, input().split())
s = [list(input()) for i in range(h)]
for x in range(h):
    for y in range(w):
        if(s[x][y] == '#'):
            up = s[max(0, x-1)][y]
            down = s[min(x+1, h-1)][y]
            right = s[x][max(0, y-1)]
            left = s[x][max(y+1, w-1)]
            if(up == '.' and down == '.' and right == '.' and left == '.'):
                print("No")
                exit()
print("Yes")
