h, w = map(int, input().split())
s = [input() for _ in range(h)]
dx = [-1, 0, 0, 1]
dy = [0, -1, 1, 0]
for i in range(h):
    for j in range(w):
        if s[i][j] == '#':
            flag = 0
            for k in range(4):
                nx = i + dx[k]
                ny = j + dy[k]
                if nx < 0 or w <= nx:
                    continue
                if ny < 0 or h <= ny:
                    continue
                if s[nx][ny] == '#':
                    flag = 1
            if flag == 0:
                print('No')
                exit()
else:
    print('Yes')
