#include <stdio.h>

int main()
{
	int s,v,t;
	scanf("%d %d",&s,&v);
	if(s/v< (float)s/v)
		t=s/v+1+10;
	else
		t=s/v+10;
	int tmp = t/60;
	int tmp1= t%60;
	if(tmp1 == 0)
		if(tmp/8<=1)
			printf("%02d:00",8-tmp);
		else
			printf("%02d:00",8+24-tmp);
	else
		if(tmp/8<=1)
			printf("%02d:%02d",7-tmp,60-tmp1);
		else
			printf("%02d:%02d",7+24-tmp,60-tmp1);
		
	return 0;
}