#include <stdio.h>

#define SIXTY 60
//---------------------------------------------------------------------------------------
//                                              Exercise 3
//                                              ----------
//
// General : The program calculates difference between 2 times.
//
// Input   : 2 times by HH:MM:SS format.
//
// Process : The program coverts the hours and minutes to seconds and calculate
//           the seconds by subtraction.
//
// Output  : Time by format HH:MM:SS.
//
//---------------------------------------------------------------------------------------
// Programmer : Cohen Idan
// Student No : None
// Date       : 09.09.2019
//---------------------------------------------------------------------------------------
void main(void)
{
    short hours1,
    minutes1,
    hours2,
    minutes2;
    int seconds1,
    seconds2;
    printf("Enter the first time (HH:MM:SS): ");
    scanf("%hd:%hd:%d", &hours1, &minutes1, &seconds1);
    printf("Enter the second time (HH:MM:SS): ");
    scanf("%hd:%hd:%d", &hours2, &minutes2, &seconds2);

    // Change the hours to minutes
    minutes1 += hours1 * SIXTY;
    minutes2 += hours2 * SIXTY;

    // Change the minutes to seconds
    seconds1 += minutes1 * SIXTY;
    seconds2 += minutes2 * SIXTY;

    // Subtraction between times as seconds
    seconds1 -= seconds2;

    // Change the seconds to minutes
    minutes1 = seconds1 / SIXTY;

    // Rest for seconds
    seconds1 %= SIXTY;

    // Change the minutes to hours
    hours1 = minutes1 / SIXTY;

    // Rest for minutes
    minutes1 %= SIXTY;
    
    printf("%02hd:%02hd:%02d\n", hours1, minutes1, seconds1);
}