//Dione Torrevillas                 CS1A                 Chapter 5, P. 294, #1
//
/**********************************************************************
 *
 * SUM OF NUMBERS
 *
 * This program asks the user to enter a positive integer.
 * It then uses a loop to add all integers from 1 up to the
 * number entered by the user.
 *
 * Computation is based on repeatedly adding each number:
 * sum = sum + count
 *
 * INPUT
 *   number       : Positive integer entered by the user
 *
 * OUTPUT
 *   sum          : Sum of all integers from 1 through number
 *
 **********************************************************************/

#include <iostream>
using namespace std;

int main()
{
    int number;     //INPUT  - Positive integer entered by user
    int count;      //CALC   - Loop counter
    int sum = 0;    //OUTPUT - Sum of the integers

    //
    // Get User Input
    //
    cout << "Enter a positive integer: ";
    cin >> number;

    //
    // Validate Input
    //
    while (number < 1)
    {
        cout << "Please enter a positive integer: ";
        cin >> number;
    }

    //
    // Compute Sum
    //
    for (count = 1; count <= number; count++)
    {
        sum += count;
    }

    //
    // Output Result
    //
    cout << "The sum of the integers from 1 to "
         << number << " is " << sum << "." << endl;

    return 0;
}