/* 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
	{
		List<List<? extends Number>> list = new ArrayList<>();
		List<List<Integer>> intList = new ArrayList<>();
		
		// Use raw types to subvert type safety...
		// list = intList; isn't otherwise allowed.
		list = (List) intList;
		
		List<Double> doubles = new ArrayList<>(Arrays.asList(0.0));
		list.add(doubles);
		
		for (List<Integer> ints : intList) {
			for (Integer i : ints) {
				System.out.println(i);
			}
		}
	}
}