#include <iostream>

double min(double n1, double n2)
{
	return n1 < n2 ? n1 : n2;
}

int main()
{
	double x;
	std::cin >> x;
	double a = sin(x), b = cos(x), c = log(abs(x));
	std::cout << min(a, min(b, c)) << std::endl;
	return 0;
}