H, W = list(map(lambda x: int(x), input().split(' ')))
table = [[c for c in input()] for _ in range(H)]

for i in range(H):
    for j in range(W):
        if table[i][j] == '#':
            if i > 1 and table[i-1][j] == '#':
                continue

            elif i < H-1 and table[i+1][j] == '#':
                continue

            elif j > 1 and table[i][j-1] == '#':
                continue

            elif j < W-1 and table[i][j+1] == '#':
                continue

            else:
                print('No')
                exit()

print('Yes')