#include<iostream>
#include<iomanip>
#include<cmath>
#define ll long long
using namespace std;
int main()
{//sqrt- pow+ fixed<<setprecision(num)/
	int s,v,ans,anss;//8*60=480
	cin>>s>>v;
	if(s%v==0)
	{
		ans=s/v;
	}
	else
	{
		ans=s/v+1;
	}
	anss=470-ans;
	//cout<<anss<<endl;
	int h,m;
	h=anss/60;//get hour
	m=anss%60;//get minute
	/*do a chance*/
	if(h<10 && m==60)//7:60
	{
		h+=1;
		cout<<"0"<<h<<":"<<"00";//08:00
	}
	else if(h<10 && m<10)//7:3
	{
		cout<<"0"<<h<<":"<<"0"<<m;//07:03
	}
	else if(h<10)//7:48
	{
		cout<<"0"<<h<<":"<<m;//07:48
	}
	else//10:48
	{
		cout<<h<<":"<<m;//10:48
	}
	return 0;
}