#include<bits/stdc++.h>
using namespace std;
int main()
{
	int s,v;
	cin>>s>>v;
	int min,h,t;
	if(s%v==0)
	{
		t=s/v;
	}
	else
	{
		t=s/v+1;
	}
	if(t>=60)
	{
		if(t%60==0)
		{
			h=t/60;
			if(h>7)
			{
				if(24-h+7>=10)
				{
					cout<<24-h+7<<":"<<"50";
				}
				else
				{
					cout<<"0"<<24-h+7<<":"<<"50";
				}
			}
			else
			{
				cout<<"0"<<7-h<<":"<<"50";
			}
		}
		else
		{
			h=t/60;
			min=t%60+10;
			if(h>=8)
			{
				if(24-h+7>=10)
				{
					if(min>=60)
					{
						cout<<24-h+6<<":"<<"0"<<120-min;
					}
					if(min<60&&min>50)
					{
						cout<<24-h+7<<":"<<"0"<<60-min;
					}
					if(min<=50)
					{
						cout<<24-h+7<<":"<<60-min;
					}
				}
				else
				{
					if(min>=60)
					{
						if(h=7)
						{
							cout<<23<<":"<<120-min;
							return 0;
						}
						cout<<6-h<<":"<<120-min;
					}
					if(min<60&&min>50)
					{
						cout<<7-h<<":"<<"0"<<60-min;
					}
					if(min<=50)
					{
						cout<<7-h<<":"<<60-min;
					}
				}
			}
		}
	}
	else
	{
		min=t;
		if(min>50)
		{
			cout<<"06"<<":"<<120-min-10;
		}
		else
		{
			if(min>40)
			{
				cout<<"07"<<":"<<"0"<<50-min;
			}
			else
			{
				cout<<"07"<<":"<<50-min;
			}
		}
	}
	return 0;
}