def fmt_latency(lat_min, lat_avg, lat_max):
    """Return formatted, rounded latency.

    :param lat_min: Min latency
    :param lat_avg: Average latency
    :param lat_max: Max latency
    :type lat_min: string
    :type lat_avg: string
    :type lat_max: string
    :return: Formatted and rounded output "min/avg/max"
    :rtype: string
    """
    try:
        t_min = int(round(float(lat_min)))
    except ValueError:
        t_min = int(-1)
    try:
        t_avg = int(round(float(lat_avg)))
    except ValueError:
        t_avg = int(-1)
    try:
        t_max = int(round(float(lat_max)))
    except ValueError:
        t_max = int(-1)

    return "/".join(str(tmp) for tmp in (t_min, t_avg, t_max))