#include <iostream>
using namespace std;
int main()
{
int c1, c2;
cin >> c1 >> c2;
int m = (c2 - c1) / 100;
if(m % 100 >= 50) {
m++;
}
int hour = m / 3600;
int minute = m % 3600 / 60;
int second = m % 60;
printf("%02d:%02d:%02d", hour, minute, second);
return 0;
}#include <iostream>
using n