include

using namespace std;

int main() { int n; while (cin >> n) {

if (n == 0) break;
int total_gold = 0;
int current_salary = 1;
int days_count = 0;

for (int i = 1; i <= n; i++) {
  total_gold += current_salary;
  days_count++;

  if (days_count == current_salary) {
    current_salary++;
    days_count = 0;
  }
}

cout << total_gold << endl;

} return 0; } //建议换成long long;