package stonehee.baekjoon;

import java.io.BufferedReader;

import java.io.IOException;

public class SaltBomb {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new java.io.InputStreamReader(System.in));

String str1 = br.readLine();

String str2 = br.readLine();

System.out.println(calculateThrowingTime(str1, str2));

}

private static String calculateThrowingTime(String now, String executeTime) {

int nowSec = convertTimeStringToInt(now);

int executeTimeSec = convertTimeStringToInt(executeTime) > nowSec ? convertTimeStringToInt(executeTime) : convertTimeStringToInt(executeTime) + (24 * 60 * 60);

return convertSecToTimeString(executeTimeSec - nowSec);

}

private static int convertTimeStringToInt(String time) {

String[] timeArr = time.split(":");

return (Integer.parseInt(timeArr[0]) * 3600) + (Integer.parseInt(timeArr[1]) * 60) + Integer.parseInt(timeArr[2]);

}

private static String convertSecToTimeString(int sec) {

int hours = 0;

int minutes = 0;

if(sec > 3600) {

hours = sec / 3600;

sec = sec - (hours * 3600);

}

if(sec > 60) {

minutes = sec / 60;

sec = sec - (minutes * 60);

}

return convertIntToTimeFormat(hours) + ":" + convertIntToTimeFormat(minutes) + ":" + convertIntToTimeFormat(sec);

}

private static String convertIntToTimeFormat(int time) {

return String.format("%02d", time);

}

}