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

dx = [-1, 0, 0, 1]
dy = [0, 1, -1, 0]
for i in range(H):
    for j in range(W):
        flag = False
        for k in range(4):
            if s[i][j] == '#':
                nx = i + dx[k]
                ny = j + dy[k]
                if nx < 0 or nx >= W or ny < 0 or ny >= H:
                    continue
                if s[nx][ny] == '#':
                    flag = True
            else:
                flag = True
        if flag == False:
            print('No')
            exit()        

print('Yes')