#include<stdio.h>
int main()
{
	int HH=7, MM=50;
	float s, v, t;
	scanf("%f %f", &s, &v);
	t = s / v;
	
	if (t != 0)/*用时不为0时*/
		MM = MM - (int)t - 1;
	
	/*时间转换*/
	while (MM >= 60)
	{
		HH++;
		MM -= 60;
	}
	while (MM < 0)
	{
		HH--;
		MM += 60;
	}
	
	/*跨天转换*/
	if (HH < 0)
	{
		HH = 24 + HH;
	}
	if (HH >= 24)
	{
		HH = 24 - HH;
	}
	
	/*输出*/
	if (HH < 10)
		printf("0");
	printf("%d:", HH);
	if (MM < 10)
		printf("0");
	printf("%d", MM);
	
	return 0;
}