#include<stdio.h>
#include<math.h>
int main(){
	int s,v,t,hour,minu;
	scanf("%d %d",&s,&v);
	t = int(ceil(s*1.0/v))+10;
	hour = (480+1440-t)/60;
	minu = (480+1440-t)%60;
	printf("%02d:%02d",hour,minu);
	return 0;
}