import math


def time_since(s):
    """compute time
    Args:
        s (float): the amount of time in seconds.
    Returns:
        (str) : formatting time.
    """
    m = math.floor(s / 60)
    s -= m * 60
    h = math.floor(m / 60)
    m -= h * 60
    return '%dh %dm %ds' % (h, m, s)