H, W = map(int, input().split())
s = [input() for i in range(H)]
flag = True
count = 0

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

for i in range(H):
    for j in range(W):
        if s[i][j] == '#':
            for k in range(4):
                if 0 <= i+dy[k] < H and 0 <= j+dx[k] < W:
                    if s[i+dy[k]][j+dx[k]] == '.':
                        count += 1
                if count == 4:
                    flag = None
                    break
                else:
                    count = 0
        else:
            pass

if flag:
    print('Yes')
else:
    print('No')
