#include <stdio.h>
#include <stdlib.h>

void readArray(int arr[], int n) {
  for (int i = 0; i < n; i++) {
    scanf("%d", &arr[i]);
  }
}

void displayArray(int arr[], int n) {
  for (int i = 0; i < n; i++) {
    printf("%d ", arr[i]);
  }
  printf("\n");
}

int countInArray(int arr[], int n, int x) {
  int count = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] == x) {
      count++;
    }
  }
  return count;
}

void removeZeros(int arr[], int *n) {
  int j = 0;
  for (int i = 0; i < *n; i++) {
    if (arr[i] != 0) {
      arr[j++] = arr[i];
    }
  }
  *n = j;
}

int isPrime(int x) {
  if (x <= 1) return 0;
  for (int i = 2; i < x; i++) {
    if (x % i == 0) {
      return 0;
    }
  }
  return 1;
}

void sortArray(int arr[], int n) {
  int i = 0, j = n - 1;
  while (i < j) {
    while (isPrime(arr[i]) && i < j) {
      i++;
    }
    while (!isPrime(arr[j]) && i < j) {
      j--;
    }
    int temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
  }
}

float avgDivisibleBy3(int arr[], int n) {
  int sum = 0, count = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] % 3 == 0) {
      sum += arr[i];
      count++;
    }
  }
  if (count == 0) return 0;
  return (float) sum / count;
}

int main() {
  int n;
  scanf("%d", &n);
  int arr[n];
  readArray(arr, n);
  printf("Original array: ");
  displayArray(arr, n);

  int x;
  scanf("%d", &x);
  int count = countInArray(arr, n, x);
  printf("%d appears %d times in the array.\n", x, count);

  removeZeros(arr, &n);
  printf("Array after removing zeros: ");
  displayArray(arr, n);

  sortArray(arr, n);
  printf("Array after sorting: ");
  displayArray(arr, n);

  float avg = avgDivisibleBy3(arr, n);
  printf("Average of numbers divisible by 3: %.2