#include<stdio.h>
int main()
{
	int s;
	int v;
	int sum;
	scanf("%d %d",&s,&v);
	if(s/v==0)
	{
		sum=s/v+10;
	}
	else
	{
		sum=s/v+10+1; 
	 } 
	if(sum>=480)
	{
		sum=sum-480;
		sum=1440-sum;
		int hour=sum/60;
	    int minute=sum%60;
	 printf("%02d:%02d",hour,minute);
		
	}
	else
	{
	sum=480-sum;
	int hour=sum/60;
	int minute=sum%60;
	printf("%02d:%02d",hour,minute);
}
	
	return 0; 
 }