def solve(field):
    for i in range(1, h + 1):
        for j in range(1, w + 1):
            if field[i][j] == '.':
                continue
            if field[i - 1][j] == field[i + 1][j] == field[i][j - 1] == field[i][j + 1] == '.':
                return False
    return True


h, w = list(map(int, input().split()))
field = ['.' + input() + '.' for _ in range(h)]
field = ['.' * w] + field + ['.' * w]
print('Yes' if solve(field) else 'No')
