#include <cmath>
#include <string>
#include <vector>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
int a, b; string s;
string calc(int x) {
	if (x <= 9) return "0" + to_string(x);
	return to_string(x);
}
int main() {
	cin >> a >> b >> s;
	int val1 = s[4] - 48;
	if (s.size() >= 6 && '0' <= s[5] && s[5] <= '9') val1 = val1 * 10 + s[5] - 48;
	val1 *= 10;
	if (s.size() >= 7 && '0' <= s[6] && s[6] <= '9') val1 += s[6] - 48;
	if (s.size() >= 8 && '0' <= s[7] && s[7] <= '9') val1 += s[7] - 48;
	val1 *= 6;
	if (s[3] == '-') val1 = -val1;
	int res = (a * 60 + b + val1 + 1440 + 900) % 1440;
	cout << calc(res / 60) << ":" << calc(res % 60) << endl;
	return 0;
}