class Main {
/**
* Returns the ISO 8601-format String corresponding to the given duration (measured in milliseconds).
*/
public static String msToIsoString(long duration) {
long milliseconds = duration % 1000;
duration /= 1000;
long seconds = duration % 60;
duration /= 60;
long minutes = duration % 60;
duration /= 60;
long hours = duration;
StringBuilder result = new StringBuilder("P");
if (hours != 0) {
result.append(hours);
result.append('H');
}
if (result.length() > 1 || minutes != 0) {
result.append(minutes);
result.append('M');
}
result.append(seconds);
if (milliseconds != 0) {
result.append('.');
result.append(milliseconds);
}
result.append('S');
return result.toString();
}
}