import java.util.*;

public class Swap
{
   public static void main(String[] args)
   {
      // Make a random array of even length between 10 and 20
      // containing numbers between 0 and 99
      Random generator = new Random();
      int n = 10 + 2 * generator.nextInt(6);
      int[] numbers = new int[n];
      for (int i = 0; i < n; i++) 
         numbers[i] = generator.nextInt(100);

      // Here is the array
      System.out.println(Arrays.toString(numbers));

      // Swap adjacent neighbors
      
      for (int i = 0; i < n; i = i + 2)
      {
         numbers[i] = numbers[i + 1];
         numbers[i + 1] = numbers[i];
      }

      // Here is the array after swapping
      System.out.println(Arrays.toString(numbers));
   }
}