// PATn.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>
#include<iomanip>

using namespace std;

int main()
{
    long long c1, c2;
    cin >> c1 >> c2;

    unsigned h, m, s;
    long long tmp = (c2 - c1)/100;
    if ((c2 - c1) % 100 > 44)
        tmp = tmp + 1;

    h = tmp / 3600;
    unsigned tmp_m = tmp % 3600;

    m = tmp_m / 60;

    s = tmp_m % 60;

    cout.fill('0');
    cout.flags(ios::right);
    cout << setw(2) << h << ":" <<setw(2)<< m << ":" <<setw(2)<< s;



    return 0;
}