03. Time + 15 Minutes

#include <iostream>

using namespace std;

int main() {
    int hours, minutes;
    cin >> hours >> minutes;

    int sumMinutes = hours * 60 + minutes + 15;
    int totalHours = sumMinutes / 60 % 24;
    int totalMinutes = sumMinutes % 60;

    if (totalMinutes < 10) {
        cout << totalHours << ":0" << totalMinutes << endl;
    }
    else {
        cout << totalHours << ':' << totalMinutes << endl;
    }

    return 0;
}

Решение с тернарен оператор:

#include <iostream>

using namespace std;

int main() {
    int hours, minutes;
    cin >> hours >> minutes;

    int sumMinutes = hours * 60 + minutes + 15;
    int totalHours = sumMinutes / 60 % 24;
    int totalMinutes = sumMinutes % 60;

    cout << totalHours << ':' << (totalMinutes < 10 ? "0" : "") << totalMinutes << endl;

    return 0;
}

Решение със setw() и setfill() на библиотеката iomanip:

#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    int hours, minutes;
    cin >> hours >> minutes;

    int sumMinutes = hours * 60 + minutes + 15;
    int totalHours = sumMinutes / 60 % 24;
    int totalMinutes = sumMinutes % 60;

    cout << totalHours << ':' << setw(2) << setfill('0') << totalMinutes << endl;

    return 0;
}