Задача 3.1

import java.util.Scanner;

public class NaVremeZaIzpit {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int examH = Integer.parseInt(sc.nextLine());
        int examMin = Integer.parseInt(sc.nextLine());
        int arrivalH = Integer.parseInt(sc.nextLine());
        int arrivalMin = Integer.parseInt(sc.nextLine());

        String late = "Late";
        String onTime = "On time";
        String early = "Early";

        int examTime = examH * 60 + examMin;
        int arrivalTime = arrivalH * 60 + arrivalMin;
        int totalMinutesDifference = arrivalTime - examTime;

        String studentArrival = late;
        if (totalMinutesDifference < -30) {
            studentArrival = early;
        } else if (totalMinutesDifference <= 0) {
            studentArrival = onTime;
        }

        String result = " ";
        if (totalMinutesDifference != 0) {
            int hoursDifference = Math.abs(totalMinutesDifference / 60);
            int minutesDifference = Math.abs(totalMinutesDifference % 60);
            if (hoursDifference > 0) {
                result = String.format("%d:%02d hours", hoursDifference,
                        minutesDifference);
            } else {
                result = minutesDifference + " minutes";
            }
            if (totalMinutesDifference < 0) {
                result += " before the start";
            } else {
                result += " after the start";
            }
        }

        System.out.println(studentArrival);
        if (!result.isEmpty()) {
            System.out.println(result);
        }

    }
}