Convert Seconds Into HH:MM:SS Format C++

This C++ program prompt the user to input the elapsed time for an event in seconds. The program outputs the elapsed time in hours, minutes, and seconds HH:MM:SS. It also outputs the input from the user.

/*
* This program will take an input of time in seconds and output it in HH:MM:SS format as well as the original time in seconds.
* By: Jesse
* Created 01/14/2015
*/

#include <iostream>

using namespace std;

int main() {
 // Declare variable
 //
 int sec = 0;
 int hrs = 0;
 int mins = 0;
 int secs = 0;
 int n = 0;

 // Request the user to enter the time in seconds
 //
 cout << "Enter elapsed time in seconds: ";
 cin >> n;

 // Sets seconds to n
 //
 sec = n;

 // Checks if input is a negative number since we can't go back in time and stops the program.
 //
 if (sec < 0) {
     cout << "Error: Sorry you can't turn back time!" << endl;
     cout << "But if you could the elapsed time would be: " << hrs << ":" << mins << ":" << secs << endl;

 system("pause");
 return (0);
 }

 // Takes the seconds and calculates the hours, minutes, and seconds.
 // 3600 seconds in 1 hour
 // 60 seconds in 1 minute
 //
 hrs = sec / 3600;
 sec = sec % 3600;
 mins = sec / 60;
 sec = sec % 60;
 secs = sec;

 // Outputs the seconds in the HH:MM:SS format then out puts the original time in seconds.
 //
     cout << "The elapsed time is: " << hrs << ":" << mins << ":" << secs << endl;
     cout << "With the entered amount of " << n << " seconds." << endl;

 system("pause");
 return (0);
}