h, w = map(int, input().split())
s = [list(input()) for i in range(h)]

dy = [0, 1, 0, -1]
dx = [1, 0, -1, 0]

flag = False
for i in range(h):
    for j in range(w):
        if s[i][j] == "#":
            for k in range(4):
                y = i + dy[k]
                x = j + dx[k]
                if 0 <= y < h and 0 <= x < w:
                    if s[y][x] == "#":
                        flag = True
            if flag == False:
                print("No")
                exit()
print("Yes")
