/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner scanIn = new Scanner(System.in);
		double x, e; 
 
		x = scanIn.nextDouble(); 
		e = scanIn.nextDouble();
 
		double sum1 = x; // в случае, когда  i=0
		double sum2 = -x * x * x / 6; // в случае, когда i=1
 
		for (int i = 2; Math.abs(1 / sum2 - 1 / sum1) >= e; i++) {
			sum1 = sum2;
			sum2 *= -x * x / ((2 * i) * (2 * i + 1)); 
		}
 
		System.out.println("1 / sum2: " + 1 / sum2);
	}
}

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LTEyCjAuNg==

-12
0.6