#include <bits/stdc++.h>
int main() {
	int delta; std::cin >> delta;
	int64_t sum(0), max(0);
	for (int iter = 0; iter < (int)1e9; iter++) {
		sum += delta;
		max = std::max(max, sum);
	}
	std::cout << max << std::endl;
	return 0;
}