#! /usr/bin/env python

def sec2str(sec):
  sign = ""
  if sec < 0:
    sign = "-";
    sec = -sec;
  sec1 = int(sec)
  sec100 = round((sec - sec1) * 100)
  minu = sec1 // 60
  sec1 = sec1 % 60
  hour = minu // 60
  minu = minu % 60
  return "%s%u:%02u:%02u.%02u" % (sign, hour, minu, sec1, sec100)