// Find the element that appear once in a sorted array.
public class AppearOnceAlt{
  public static void main(String[] args){
     int[] arr = new int[]{1,1,1,1,2,2,3,4,4,4,4,5};
     appear(arr);
  }

  public static void appear(int[] arr){
   int elem = arr[0];
   int old = elem;
    int count = 0;
   for(int i = 1;i<arr.length;i++){
       elem  = arr[i];
       if(elem == old){ count ++;}
       else{
          if(count == 0 || i == (arr.length -1)){ System.out.println(">" +((count == 0)?old:elem)); }
          count = 0;
       }
       old = elem;
   }
  }
}