import java.util.Scanner;

public class _04_Fourth {
    public static void main(String args[]) {
        Scanner input = new Scanner(System.in);
        String h1= input.nextLine();
        String h2 = input.nextLine();
        String[] hour1 = h1.split(":");
        String[] hour2 = h2.split(":");


        int startHour = Integer.parseInt(hour1[0]);
        int startMin = Integer.parseInt(hour1[1]);
        int startSec = Integer.parseInt(hour1[2]);
        int endHour = Integer.parseInt(hour2[0]);
        int endMin = Integer.parseInt(hour2[1]);
        int endSec = Integer.parseInt(hour2[2]);
        int resHour = 0;
        int resMin = 0;
        int resSec = 0;
        String resultHour="";
        String resultMin="";
        String resultSec="";
        if (startHour==0 && startMin == 0){
            resSec = startSec - endSec;

        }
        else if (startSec < endSec){
            startSec = startSec + 60;
            startMin --;
            if (startMin < endMin){
                startMin = startMin + 60;
                startHour--;
            }
            resHour = startHour - endHour;
            resMin = startMin - endMin;
            resSec = startSec - endSec;


        }
        else if (startMin < endMin){
            startMin= startMin + 60;
            startHour --;
            resHour = startHour - endHour;
            resMin = startMin - endMin;
            resSec = startSec - endSec;

        }
        else{
            resHour = startHour - endHour;
            resMin = startMin - endMin;
            resSec = startSec - endSec;
        }

        resultHour = "" + resHour;
        if (resMin < 10){
            resultMin = "0" + resMin;
        }
        else
            resultMin = "" + resMin;

        if (resSec < 10){
            resultSec = "0" + resSec;
        }
        else
            resultSec = "" + resSec;

        System.out.println(resultHour + ":" + resultMin + ":" + resultSec);





    }
}