import java.util.*;

public class Main {
    public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            int s = sc.nextInt(), v = sc.nextInt();
            int needHour = s / v / 60 % 24;
            int temp = s % v == 0 ? s / v : (s / v + 1);
            int needMin = temp % 60;
            int finalHour = 7 - needHour, finalMin = 50 - needMin;
            if (needHour > 7) {
                finalHour = 31 - needHour;
            }
            if (finalMin < 0) {
                finalMin += 60;
                finalHour = finalHour - 1 <= 0 ? 23 : finalHour - 1;
            }
            System.out.printf("%02d:%02d", finalHour, finalMin);
    }
}