import java.util.*;

class UseArrayLists15
// Shows constructively removing the integer before all occurrences of 
// an integer in an ArrayList
{
 public static void main(String[] args) throws Exception
 {
  Scanner input = new Scanner(System.in);
  System.out.println("Enter some numbers (all on one line, separated by spaces):");
  String line = input.nextLine();
  String[] numbers = line.split(" +");
  ArrayList<Integer> a = new ArrayList<Integer>();
  for(int i=0; i<numbers.length; i++)
      a.add(new Integer(numbers[i]));
  System.out.println("The numbers are stored in an ArrayList");
  System.out.println("\nThe ArrayList is "+a);
  System.out.print("\nEnter a number: ");
  int p = input.nextInt();
  System.out.println("Remove the number before every "+p+" in the ArrayList");
  ArrayList<Integer> b = removeBefore(a,p);
  System.out.println("\nThe result is "+b);
 }

 public static ArrayList<Integer> removeBefore(ArrayList<Integer> a,int m)
 // Removes the number which occurs before every occurrence of m in a, 
 // does this costructively
 {
  ArrayList<Integer> b = new ArrayList<Integer>();
  for(int i=0; i<a.size()-1; i++)
     if(!a.get(i+1).equals(m))
         b.add(a.get(i));
  b.add(a.get(a.size()-1));
  return b;
 }
}