public class Finder {
    static int MissingElement(int[] array, int[] array2) {
        int x = 0, counter = 0;
        for (int i = 0; i < array.length; i++) {
            if (counter == 1) { break; }
            x = array[i];
            for (int j = 0; j < array2.length; j++) {
                if (x == array2[j]) { counter = 2; break; } else  { counter = 1; }
            }
        } return x;
    }

 public static void main (String[] args) {
     int[] array = {4, 8, 12, 9, 3};
     int[] array2 = {4, 8, 9, 3};
     System.out.println("Missing element: " + Finder.MissingElement(array, array2));
  }
}