H, W = map(int, input().rstrip().split())
s =[list(input().rstrip()) for _ in range(W)]
colors = [['.' for _ in range(W)] for _ in range(H)] 
search = [[-1, 0], [0, -1], [0, 1], [1, 0]]

judge = True
for i in range(H):
    for j in range(W):
        if s[i][j] =='#':
            flag = 0
            for k in range(len(search)):
                x = i + search[k][0]
                y = j + search[k][1]
                if 0 <= x < H and 0 <= y < W and s[x][y] == '#':
                    colors[i][j] = colors[x][y] = '#'
                    flag = 1
                    if flag == 0:
                        judge = False
                        
if s != colors:
    judge = False

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