05.Time + 15 Minutes

import java.util.Scanner;

public class TimeAfter15Minutes_05 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        //read hour, minutes
        int hour = Integer.parseInt(scanner.nextLine()); //23
        int minutes = Integer.parseInt(scanner.nextLine()); //59
        //calculate total in minutes = hour * 60 + minutes
        int totalInMinutes = hour * 60 + minutes; // 1439
        int totalInMinutesPlus15 = totalInMinutes + 15; //1439 + 15 = 1454

        //calculate endHour = totalAfter15 / 60
        //calculate endMinute = totalAfter % 60

        int endHour = totalInMinutesPlus15 / 60; //24
        int endMinutes = totalInMinutesPlus15 % 60; //14

        if(endHour == 24){
           endHour = 0;
        }

        //print hour:minute
        System.out.printf("%d:%02d",endHour, endMinutes);

    }
}