H, W = map(int, input().split())
matrix = []
for _ in range(H):
    row = input().split()
    matrix.append(row)
no_flag = False
for i, x in enumerate(matrix):
    for j, y in enumerate(matrix[i]):
        if y == '#':
            if j != 0 and matrix[i][j - 1] == '#':
                continue
            elif j != W - 1 and matrix[i][j + 1] == '#':
                continue
            elif i != 0 and matrix[i - 1][j] == '#':
                continue
            elif i != H - 1 and matrix[i + 1][j] == '#':
                continue
            else:
                no_flag = True
                break
    if no_flag == True:
        print('No')
        break
else:
    print('Yes')