/* 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
	{
		// your code goes here
double nivelComb = 13;
double raio = 15;
double vol = (1.0/3.0) * Math.PI * Math.pow(nivelComb,2) * (3 *raio - nivelComb);
System.out.printf("%.3f", vol);
	}
}

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