#include <iostream>
using namespace std;
int main()
{
int a;
int result = 0;
cin >> a;
while (a <= 500)
result += a;
a ++;
}
cout << result << endl;
return 0;
#include <iostream>
using namespace std;
int main()
{
int a;
int result = 0;
cin >> a;
while (a <= 500)
{
result += a;
a ++;
}
cout << result << endl;
return 0;
}