Timespan

import java.util.Scanner;
public class problem01 {
	public static void main(String[] args) {
		@SuppressWarnings("resource")
		Scanner scanner = new Scanner(System.in);
		String start = scanner.nextLine();
		//scanner.nextLine();
		String end = scanner.nextLine();

		String[] startTime=start.split(":");
		String[] endTime=end.split(":");
		int sumStartSeconds=0;
		int sumEndSeconds=0;



			int startHours = Integer.parseInt(startTime[0]);
			int startMinutes = Integer.parseInt(startTime[1]);
			int startSeconds = Integer.parseInt(startTime[2]);
			sumStartSeconds=startHours*3600+startMinutes*60+startSeconds;

			int endHours = Integer.parseInt(endTime[0]);
			int endMinutes = Integer.parseInt(endTime[1]);
			int endSeconds = Integer.parseInt(endTime[2]);
			sumEndSeconds=endHours*3600+endMinutes*60+endSeconds;

		int timeSpam=sumStartSeconds-sumEndSeconds;

		int totalHours=timeSpam/3600;
		int totalMinutes=(timeSpam-totalHours*3600)/60;
		int totalSeconds=(timeSpam-totalHours*3600)%60;
		System.out.printf("%d:%02d:%02d",totalHours,totalMinutes,totalSeconds);
	}
}