#include<stdio.h>
#include<math.h>
int main() {
	int s, v;
	scanf("%d %d", &s,&v);
	if (s < 1 || v < 1 || s>10000 || v>10000) return 0;
	int t1 = s / v;
	int t2 = s % v;
	if (t2 != 0) t1 += 1;
	t1 += 10;
	if (t1 >= (24 * 60)) return 0;
	int hour = 7 - t1 / 60;
	int min = 60 - t1 % 60;
	while (min >= 60) {
		hour += 1;
		min = 0;
	}
	while(hour < 0) hour += 24;
	if (hour == 24) hour = 0;
	if (hour > 10) {
		printf("%d:", hour);
	}
	else
		printf("0%d:", hour);
	if (min > 10)
		printf("%d", min);
	else
		printf("0%d",min);
	return 0;
}