#include "pch.h"
#include <iostream>
using namespace std;
int main()
{
    int a;
    int b= 0 ;
    cout << "Vedite chislo a ot 0 do 500 \n";
    cin >> a;
    if (a >= 500) a = 499;
    for (int i = a; i < 501; i++)
    {
        b += i;
    }
    cout << b;
}