#include<stdio.h>
#include<math.h>
int main()
{
	int s,v;
	int time,h,m;
	scanf("%d%d",&s,&v);
	time=s/v+10;
	h=time/60;
	m=time%60;
	if(h<=8)
	{
		if(m==0)
		printf("%02d:%02d",8-h,m);
		else
		{
			if(h==8)
			printf("23:%02d",60-m-1);
			else
			printf("%02d:%02d",7-h,60-m-1);
		}
	}
	else
	{
		if(m==0)
		printf("%02d:%02d",16+h,m);
		else
		printf("%02d:%02d",15+h,60-m-1);
	}
	return 0;
}