/* 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
	{
		System.out.print(starString(-1));
	}
 
 
	public static String starString(int n){
 
    if(n<0){
       String output = "";
       return output = "IllegalArgumentException";
    }else{
        String stars = "";
        for(int i = 0; i < Math.pow(2, n); i++){
            stars += "*";
        }
          return stars;
    }
}
}

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