#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

const double PI = 3.141592653589793238463;
 
int main() {
	double cos_pi_2 = cos(PI/2);
	
	cout << ((cos_pi_2 < 0.0001 && cos_pi_2 > -0.0001) ? 0 : cos_pi_2) << endl;
}