#include <iostream>

#include <cmath>

using namespace std;

​

int main() {

  cout << atan(0.5) << "\n";

  cout << atan(-0.5) << "\n";

  cout << atan(5) << "\n";

  cout << atan(-5) << "\n";

  cout << atan(100) << "\n";

  cout << atan(-100) << "\n";

  return 0;

}

​