#include<iostream>

using namespace std;

int s, v,minute,hour;
int main()
{
	cin >> s >> v;
	//得出走过去的用时
	if (s % v == 0)
	{
		minute = s / v;
	}
	else
	{
		minute = s / v + 1;
	}
	minute += 10;//垃圾分类时间

	//得出要用的小时
	
	if (minute % 60 == 0)
	{
		hour = minute / 60;
	}
	else
	{
		hour = minute / 60 + 1;
	}
	minute %= 60;

	
	if (hour < 8 && minute>0)
	{
		printf("%02d:%02d", 8 - hour,60-minute);
	}
	else if (hour < 8 && minute == 0)
	{
		printf("%02d:%02d", 8 - hour,0);
	}
	else if (hour == 8 && minute == 0)
	{
		printf("00:00");
	}
	else if (hour > 8 && minute == 0)
	{
		printf("%02d:%02d", 32 - hour, 0);
	}
	else if (hour > 8 && minute > 0)
	{
		printf("%02d:%02d", 32 - hour, 60-minute);
	}


	return 0;
}