#include<stdio.h>
main()
{
	int s,v,shi,fen;
	int t,f;
	scanf("%d %d",&s,&v);
	if(s%v==0);
	   {t=s/v;}
	if(s%v!=0)
	   {t=s/v+1;}
	for(;t>1440;t=t-1440);
	if (t<=470)
	{
	   f=480-10-t;
	   shi=f/60;
	   fen=f%60;
	   printf("%02d:%02d",shi,fen);
   }
   else 
   {
    	f=1440-10-t;
      shi=f/60;
	   fen=f%60;
	   printf("%02d:%02d",shi,fen);
	 }
}