#include<cmath>
using namespace std;
 
int main() {
	int s,v;
	int d;
	scanf("%d%d",&s,&v);
	if(s%v==0){
		d=s/v;
	}
	else{
		d=s/v+1;
	}
	if(d/60>23){
		cout<<"08:00"<<endl;
		return 0;
	}
	int minute;
	if(50-d%60>=0){
		minute=50-d%60;
	}
	else {
		minute=110-d%60;
	} 
	int hour;
	if(7-d/60>=0){
		hour=7-d/60;
	}
	else{
		hour=31-d/60;
	}
	if(hour>=10&&minute>=10){
		printf("%d:%d",hour,minute);
	}
	if(hour<10&&minute>=10){
		printf("0%d:%d",hour,minute);
	}
	if(hour>=10&&minute<10){
		printf("%d:0%d",hour,minute);
	}
	if(hour<10&&minute<10){
		printf("0%d:0%d",hour,minute);
	}
	return 0;
}