#include <stdio.h>
int main(){
	int s,v,hour,h2,min1,min2,time;
	scanf("%d%d",&s,&v);
	if(s%v==0) time=s/v+10;
	else time=s/v+11;
	if(time<=480){
		if(time%60==0) hour=time/60;
		else hour=time/60+1;
		min1=time%60;
		min2=60-min1;
		h2=8-hour;
		}
		else{
		if(time%60==0) hour=time/60;
		else hour=time/60+1;
		min1=time%60;
		min2=60-min1;
		h2=32-hour;	
		}
	if(min2<10) printf("%2d:0%d",h2,min2);
	else 
	printf("%2d:%2d",h2,min2);
	return 0;
}