Timespan

import java.util.Scanner;

public class Timespan {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] start = sc.nextLine().split(":");
        String[] end = sc.nextLine().split(":");
        int startHours = Integer.parseInt(start[0]);
        int startMinutes = Integer.parseInt(start[1]);
        int startSeconds = Integer.parseInt(start[2]);
        int endHours = Integer.parseInt(end[0]);
        int endMinutes = Integer.parseInt(end[1]);
        int endSeconds = Integer.parseInt(end[2]);
        int timespan = 0;
        int hours = startHours - endHours;
        int minutes = startMinutes - endMinutes;
        int seconds = startSeconds - endSeconds;
        if (seconds < 0) {
            seconds = 60 + seconds;
            minutes--;
        }
        if (minutes < 0) {
            minutes = 60 + minutes;
            hours--;
        }
        System.out.printf("%d:%02d:%02d", hours, minutes, seconds);
    }

}