#include<iostream>
using namespace std;

int main()
{
	int m=0,h=8,m_p=0,h_p=0;
	float s, v;
	cin >> s >> v;
	m_p = ceil(s / v);
	if (m_p > 8 * 60)
	{
		h = 24;
		m_p -= 8 * 60;
	}
	if ((m_p+10) > 60)
	{
		m_p=(m_p+10)%60;
		h_p = (m_p+10) / 60;
	}
	h = h - h_p - 1;
	m = 50 - m_p;
	if (m < 10&&h<10)
	{
		cout << 0 << h << ':' << 0 << m;
	}
	else if(m<10&&h>=10)
	{
		cout << h << ':' << 0 << m;
	}
	else if (m >= 10 && h >= 10)
	{
		cout << h << ':' << m;
	}
	else if (m >= 10 && h < 10)
	{
		cout << 0 << h << ':' << m;
	}


	return 0;
}