#include<stdio.h>
int main() {
int c1, c2,s;
scanf("%d%d", &c1, &c2);
int sum = c2 - c1;
if (sum % 100 >= 50)
s = sum / 100 + 1;
else
s = sum / 100;
printf("%.2d:%.2d:%.2d", s / 3600, s%3600/60, s % 60);
//system("pause");
return 0;
}
#include<stdio.h>
int main() {
int c1, c2,s;
scanf("%d%d", &c1, &c2);
int sum = c2 - c1;
if (sum % 100 >= 50)
s = sum / 100 + 1;
else
s = sum / 100;
printf("%.2d:%.2d:%.2d", s / 3600, s%3600/60, s % 60);
//system("pause");
return 0;
}