package com.company;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class Problem1 {

    public static void main(String[] args) throws ParseException {
        Scanner input = new Scanner(System.in);
        String[] time = input.nextLine().split(":");
        int hour = Integer.parseInt(time[0]);
        int minutes = Integer.parseInt(time[1]);
        int seconds = Integer.parseInt(time[2]);
        time = input.nextLine().split(":");
        hour -= Integer.parseInt(time[0]);
        minutes -= Integer.parseInt(time[1]);
        seconds -= Integer.parseInt(time[2]);
        if (seconds < 0){
            minutes --;
            seconds += 60;
        }
        if (minutes < 0){
            hour --;
            minutes += 60;
        }
        System.out.printf("%d:%02d:%02d",hour,minutes,seconds);

    }
}