#include<stdio.h>
#include<math.h>

int main()
{
	int sytime;
	int HH = 0, MM = 0;
	double s, v;
	int time;
	scanf("%lf %lf", &s, &v);
	time = s / v;
	if (time == 470) {
		time = time + 10;
	}
	else {
		time = time + 1 + 10;
	}
	if (time < 480) {
		sytime = 480 - time;
		HH = sytime / 60;
		MM = sytime % 60;
		printf("%.2d:%.2d", HH, MM);

	}
	if (time == 480) {
		printf("%.2d:%.2d", HH, MM);

	}
	if (time > 480 ) {
		time = time - 480;
		sytime = 1440 - time;
		HH = sytime / 60;
		MM = sytime % 60;
		printf("%.2d:%.2d", HH, MM);

	}
	

	return 0;
}