h, w = map(int,input().split())
# In[]
s = [list(input()) for _ in range(h)]
dx = [0,1,0,-1]
dy = [1,0,-1,0]

count = 0

for y in range(h):
    for x in range(w):
        cnt = 0
        for k in range(4):
            ny = y + dy[k]
            nx = x + dx[k]
            if nx < 0 or nx>=w or ny < 0 or ny >=h:
                continue
            if s[y][x] == '.':
                continue
            if s[y][x] == '#':
                if s[ny][nx] == '#':
                    cnt += 1
        if cnt == 0:
            print('No')
            exit()

                        
print('Yes')
