#include<bits/stdc++.h>
using namespace std;
int s,v,t,sumt,minute,hour;
int main()
{
	cin>>s>>v;
	t=ceil(s/v)+10;
	sumt=8*60+24*60;
	sumt-=t;
	if(sumt>=24*60)
		sumt-=24*60;
	if(sumt%60==0)
		minute=sumt%60;
	else
		minute=sumt%60-1;
	hour=sumt/60;
	if(minute==60)
	{
		hour+=1;
		cout<<hour<<":00";
	}
	else
	{
		if(hour<10)
		{
			if(minute<10)
				cout<<"0"<<hour<<":0"<<minute;
			else
				cout<<"0"<<hour<<":"<<minute;
		}
		else
		{
			if(minute<10)
				cout<<hour<<":0"<<minute;
			else
				cout<<hour<<":"<<minute;
		}
	}
	return 0;
}