Çàäà÷à . Ïîïàðíàÿ ïåðåñòàíîâêà

import java.util.ArrayList;
import java.util.Scanner;
public class Main
{
    public static void main(String[] args) {
        int n;
        Scanner in = new Scanner(System.in);
        n = in.nextInt();

        ArrayList<Integer> arr = new ArrayList<Integer>();

        for(int i=0;i<n;i++) {
            int a = in.nextInt();
            arr.add(a);
        }
   

    for (Integer a: arr)
              {
                System.out.print(a+" ");
        }
    }
}