#include<iostream>

using namespace std;

int main()
{
	double s, v, t;
	int min = 50, hour=7;
	cin >> s >> v;
	t = ceil(s / v);
	if (t <= 50)
	{
		cout << "07:" << min - t << endl;
	}
	else if(t>50 && t<470)
	{
		hour = 7 - ceil((t - 50) / 60);
		min = 50 + (ceil((t - 50) / 60)*60) - t;
		cout << "0" << hour << ":" << min << endl;
	}
	else if (t == 470)
	{
		cout << "00:00" << endl;
	}
	else if (t > 470)
	{
		hour = 24 - ceil((t - 470) / 60);
		min = ceil((t - 470) / 60)*60 + 470 - t;
		if (hour == 24)
		{
			cout << "00:00" << endl;
		}

		if (hour < 10)
		{
			cout << "0" << hour << ":" << min << endl;
		}
		else
		{
			cout << hour << ":" << min << endl;
		}
	}
	return 0;
}