function exam(examHour, examMinutes, arriveHour, arriveMinutes) {

    examHour = Number(examHour);
    examMinutes = Number(examMinutes);
    arriveHour = Number(arriveHour);
    arriveMinutes = Number(arriveMinutes);

    let allExamMins = ((examHour * 60) + examMinutes);
    let allArriveMins = ((arriveHour * 60) + arriveMinutes);
    let time = '';
    let hours = 0;
    let minutes = 0;
    let minsDifference = 0;


    if (allArriveMins > allExamMins) {
        time = 'Late';
        console.log(time);

    } else if (allExamMins - allArriveMins <= 30) {
        time = 'On time';

    } else {
        time = 'Early';
        console.log(time);
    }

    let result = Math.abs(allArriveMins - allExamMins);

    if (time === 'Late') {
        if (examHour <= arriveHour) {
            hours = arriveHour - examHour;
            minutes = arriveMinutes - examMinutes;
            minsDifference = allArriveMins - allExamMins;
        }
        if (minsDifference < 60) {
            console.log(`${minsDifference} minutes after the start`);

        } else if (minsDifference >= 60 && minutes < 10) {
            console.log(`${hours}:0${minutes} hours after the start`);

        } else {
            minutes = minsDifference % 60;
            console.log(`${hours}:${minutes} hours after the start`);
        }

    } if ((time === 'On time') && (examMinutes === arriveMinutes)) {
        console.log(`On time`);

    } else if (time === 'On time' && minsDifference <= 30) {
        minsDifference = allExamMins - allArriveMins;
        console.log('On time');
        console.log(`${minsDifference} minutes before the start`);

    } if (time === 'Early') {
        if (allExamMins - allArriveMins < 60) {
            minsDifference = allExamMins - allArriveMins;
            console.log(`${minsDifference} minutes before the start`);

        } else {
            hours = examHour - arriveHour;
            minutes = examMinutes - arriveMinutes;
            if (minutes < 10) {
                console.log(`${hours}:0${minutes} hours before the start`);
            }
        }
        }else {
            console.log(`${hours}:${minutes} hours before the start`);

    }
}