#include<stdio.h>
int cut(double input);
int main()
{
	int s, v;
	int hours = 0;
	int final;
	scanf("%d%d", &s, &v);
	double time_cost;
	time_cost = (double)s / v+10.0;
	final = cut(time_cost) ;
	while (final >= 60.0)
	{
		final = final - 60;
		hours++;
	}
	if (hours == 0)
	{
		printf("07:%d", 60 - final);
		return 0;
	}
	if (hours < 8)
	{
		if (final == 0)
		{
			printf("0%d:00", 8 - hours);
			return 0;
		}
		if (60-final >= 10)
		{
			printf("0%d:%d", 7 - hours, 60-final);
			return 0;
		}
		else
		{
			printf("0%d:0%d", 7 - hours, 60-final);
		}
	}
	if (hours == 8)
	{
		if (final == 0)
		{
			printf("00:00");
			return 0;
		}
		if (final >= 10)
		{
			printf("00:%d", final);
			return 0;
		}
		else
		{
			printf("00:0%d", final);
		}
	}
	if (hours > 8)
	{
		if (final == 0)
		{
			printf("%d:00", 32 - hours);
			return 0;
		}
		if (60-final >= 10)
		{
			printf("%d:%d", 32-hours-1, 60-final);
			return 0;
		}
		else
		{
			printf("%d:0%d", 32-hours-1, 60-final);
		}
	}
}
int cut(double input)
{
	double rest = input - (int)input;
	if (rest - 0.00000 > 0)
		return (int)input + 1;
	return (int)input;
}