import java.util.*;
 
class Main
{
	public static void main (String[] args)
	{
		Scanner in = new Scanner(System.in);
		double a, y;
		a = in.nextDouble();
		if (a < -1){
			y = 1/(a*a);
		}
		else{
			if (a >= -1 && a <= 2) y = a*a;
			else y = 4;
		}
		System.out.printf("%.8f\n", y);
	}
}