#include<bits/stdc++.h>
using namespace std;
int main()
{
	int s,v,xs,fz,hh,mm,time;
	cin>>s>>v;
	if(time%v!=0)
		time=s/v+11;
	else
		time=s/v+10;
	xs=time/60;
	fz=time%60;
	if(xs<8)
	{
		if(fz==0)
		{
			hh=8-xs;
			mm=fz;
		}
		else
			hh=8-xs-1;
			mm=60-fz;
	}
	else if(xs>=8)
	{
		if(fz==0)
		{
			hh=32-xs;
			mm=60-fz;
		}
		else
			hh=32-xs-1;
			mm=60-fz;
	}
	if(hh<10)
		cout<<'0'<<hh<<':';
	else
		cout<<hh<<':';
	if(mm<10)
		cout<<'0'<<mm;
	else
		cout<<mm;
}