#include <stdio.h>
#include <math.h>
#include <iostream>
#include <stdlib.h>
using namespace std;
int main()
{
    long int range, total = 0;
    cin >> range;
    if ( range <= 0 && abs(range) < 10000 )
    {
        for ( int x = 1; x >= range; --x )
            total += x;
        cout << total << endl;
    }
    else if ( range > 0 && abs(range) < 10000 )
    {
        for ( int x = 1; x <= range; ++x )
            total += x;
        cout << total << endl;
    }



    return 0;
}

Edited by author 22.11.2014 20:22