import java.util.*;

/*For this program, I'm going to assume we have a simple
 * list of pairs. Nothing more.
 *IMPORTANT: You'll need to be more careful with your generics!
 */
public class Demo {
	public Demo() {
		ArrayList<ArrayList<Integer>> list=new ArrayList<>();
		populateList(list);
		System.out.println("Starting:");
		displayList(list);
		
		//Now, let's count the total contents
		System.out.println("Total members: "+countify(list));
		
		//Next, let's remove the first instance of a pair that includes '4' (also happens to be the only)
		obliterate(4,list);
		
		//Now, let's see the result!
		displayList(list);
	}
	
	//Generates a list of {{2,6},{4,12},{6,18}, {8,24}, {10,30}}
	private void populateList(ArrayList<ArrayList<Integer>> list) {
		for (int i=2;i<=10;i+=2) {
			ArrayList<Integer> pair=new ArrayList<>();
			pair.add(i); pair.add(i*3);
			list.add(pair);
		}
	}
	
	private void displayList(ArrayList<ArrayList<Integer>> list) {
		for (ArrayList<Integer> pair:list) {
			System.out.print("{");
			for (int value:pair) {
				System.out.print(" "+value);
			}
			System.out.println(" }");
		}
	}
	
	private int countify(ArrayList<ArrayList<Integer>> list) {
		int sum=0;
		for (ArrayList<Integer> pair:list) sum+=pair.size();
		return sum;
	}
	
	private void obliterate(int target, ArrayList<ArrayList<Integer>> list) {
		//THIS ALGORITHM DOESN'T REALLY RESEMBLE WHAT YOU'LL BE DOING
		//IT ONLY DEMONSTRATES THAT REMOVING AN ENTRY FROM THE LIST IS SIMPLE
		//Also, you should probably use a 'for' loop here, but... didn't feel like it
		int idx=0;
		while (idx<list.size()) {
			//seriously, not the same algorithm as yours. Yours relies only on the size of groups;
			//  this one actually goes inside to inspect contents
			ArrayList<Integer> pair=list.get(idx);
			//Yeah, a 'loop for 2' is slightly silly
			for (int value:pair)
				if (value==target) {
					list.remove(idx);
					return;
				}
			idx++;
		}
	}
	
	/*Important details to remember:
	 *I'm only using 'Integer' because we don't have an E here. But YOU DO.
	 *    So don't use String!
	 *I'm only doing things like output here because we don't have a clinet.
	 *    But YOU DO. Don't do print statements anywhere within your queue!
	 */
	
	public static void main(String[] args) {new Demo();}
}