#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
	int s,v,t;
	cin>>s>>v;
	t=s/v;
	if(s%v!=0){
		//TODO
		t++;
	}
	int hour=7,min=50;
	int t_h=t/60;
	int t_m=t%60;
	hour-=t_h;
	min-=t_m;
	if(min<0){
		min+=60;
		hour-=1;
	}
	if(hour<=0){
		//TODO
		hour+=24;
	}
	if(hour>10&&min>10){
		//TODO
		cout<<hour<<":"<<min<<endl;
	}
	else if(hour<10&&min>10){
		cout<<"0"<<hour<<":"<<min<<endl;
	}
	else if(hour>10&&min<10){
		cout<<hour<<":"<<"0"<<min<<endl;	
	}
	else{
		cout<<"0"<<hour<<":"<<"0"<<min<<endl;
	}
	return 0;
}