/* 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
	{
		Deque<ArrayList<Integer>> unitPaths = new ArrayDeque<>();
		ArrayList<Integer> path = new ArrayList<>();
		unitPaths.push(new ArrayList<>(path));
 
		System.out.println(path.size()); // 0
		System.out.println(unitPaths.peek().size()); // 0
 
		path.add(7);
		System.out.println(path.size()); // 1
		System.out.println(unitPaths.peek().size()); // 0
	}
}

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