#include<stdio.h>

int main()
{
	int s,v,time,hour,minute,h,m;
	scanf("%d%d",&s,&v);
	
	if(s>10000||v>=10000)
	return 0;
	
	if(s%v==0)
	  time=s/v;
	else
	  time=s/v+1;
	time=time+10;
	if(time>480) return 0;
	
	hour=time/60;
	minute=time%60;

    if(minute==0)
    {
    	h=8-hour;
    	m=0;
    	printf("0%d:00",h);
	}
	else
	{
		h=7-hour;
		m=60-minute;
		if(m>10)
		  printf("0%d:%d",h,m);
		else
		  printf("0%d:0%d",h,m);
	}
	return 0;
}