#include <iostream>
#include <cmath>
int main() {
double x;
std::cin >> x;
if (1. 0 < x <= 12. 5) {
std::cout << 3 * pow(x, -3) << std::endl;
} else if (x > 12. 5) {
std::cout << 13. 44 << std::endl;
} else if (-15. 4 <= x <= 1. 0) {
std::cout << atan(abs(x + 1)) << std::endl;
} else {
std::cout << 1 << std::endl;
}
return 0;
}