```C++
String timeCalc(uint32_t t) {
	uint32_t timer = t / 1000;
	uint32_t timeSec = (timer % 3600) % 60;
	uint32_t timeMin = (timer % 3600) / 60;
	uint32_t timeHour = timer / 3600 % 24;
	uint32_t timeDay = timer / 60 / 60 / 24;
	String s = "";
	s += timeDay;
	s += ":";
	if (timeHour < 10)
		s += "0";
	s += timeHour;
	s += ":";
	if (timeMin < 10)
		s += "0";
	s += timeMin;
	s += ":";
	if (timeSec < 10)
		s += "0";
	s += timeSec;
	return s;
}
```