#include <stdio.h>
int round_off(double n){
	if(n==int(n)) return (int)n;
	else return int(n)+1;
}

int main(){
	double s,v;
	scanf("%lf %lf",&s,&v);
	int time,h,m;
	time=round_off(s/v)+10;
	if((float)time/60<=8)
	{
		if(time/60==0){
		    h=7;m=60-time;
	    }else{
	    	h=7-time/60;
	    	m=60-time%60;
    	}
	}
	else if((float)time/60<=12)
	{
		time=time-8*60;
		if(time/60==0){
			h=23;m=60-time;
		}else{
			h=23-time/60;
			m=60-time%60;
		}
	}
	else{
		h=8;m=1;
	}
	
	printf("%02d:%02d",h,m);
	return 0;
}