import java.util.*;public class DemoTest5 {public static void main(String[] args) {Scanner in = new Scanner(System.in);// 注意 hasNext 和 hasNextLine 的區別while (in.hasNextLine()) { // 注意 while 處理多個 caseint a =in.nextInt();int[] arr =new int[a];for(int i=0;i<a;i++){arr[i]=in.nextInt();}int c= in.nextInt();solve(arr,c);}}private static void solve(int[] arr,int c) {HashMap<Integer,Integer> map = new HashMap<>();for(int i = 0;i<arr.length;i++){map.put(arr[i],map.getOrDefault(arr[i],0)+1);}int count = 0;for(Map.Entry<Integer,Integer> entry:map.entrySet()){if(entry.getValue()>=c){count++;}}if(count == 0){System.out.println(0);return;}System.out.println(count);map.entrySet().stream().filter(entry-> entry.getValue()>=c).sorted((e1, e2)-> {if(Objects.equals(e2.getValue(), e1.getValue())){return e1.getKey()-e2.getKey();}else{return e2.getValue()-e1.getValue();}}).forEach(entry->{System.out.println(entry.getKey());});}
}