#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
int main()
{
	float 	s, v;
	float t;
	cin >> s >> v;
	t = s / v;
	if (t != (int)t)
		t = t++;
	t = int(t);
	int hour1, minute1;
	hour1 = t / 60;
	minute1 = (int)t % 60;
	for (;hour1 >= 24;)
	{
		if (hour1 >= 24)
			hour1 -= 24;
	}
	int hour = 7, minute = 50;
	hour = hour - hour1;
	minute = minute - minute1;
	if (minute < 0)
	{
		minute += 60;
		hour--;
	}
	if (hour < 0)
		hour += 24;
	cout << setw(2) << setfill('0') << hour << ':' << setw(2) << setfill('0') << minute << endl;
	return 0;
}