#include <bits/stdc++.h>
using namespace std;
vector<bool> primes(2000001, true);
bool isPrime(int num) { return primes[num]; }
void buildPrimes() {
  for (int i = 2; i <= 2000000; i++) {
    if (!primes[i]) {
      continue;
    }
    int j = 2 * i;
    while (j <= 2000000) {
      primes[j] = false;
      j += i;
    }
  }
}
int main() {
  cin.sync_with_stdio(0);
  int n;
  cin >> n;
  vector<int> nums(n);
  for (int i = 0; i < n; i++) {
    cin >> nums[i];
  }
  buildPrimes();
  sort(nums.begin(), nums.end());
  if (n == 1) {
    cout << 1 << endl;
    cout << nums[0] << endl;
    return 0;
  }
  int count = 0;
  for (int i = 0; i < n; i++) {
    if (nums[i] == 1) {
      count++;
      continue;
    }
    break;
  }
  if (count < 2) {
    for (int i = 0; i < n; i++) {
      for (int j = i + 1; j < n; j++) {
        int sum = nums[i] + nums[j];
        if (isPrime(sum)) {
          cout << 2 << endl;
          cout << nums[i] << ' ' << nums[j] << endl;
          return 0;
        }
      }
    }
    cout << 1 << endl;
    cout << nums[0] << endl;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    if (nums[i] == 1) {
      continue;
    }
    int sum = nums[i] + 1;
    if (isPrime(sum)) {
      cout << count + 1 << endl;
      for (int i = 0; i < count; i++) {
        cout << "1 ";
      }
      cout << nums[i] << endl;
      return 0;
    }
  }
  cout << count << endl;
  for (int i = 0; i < count; i++) {
    cout << "1 ";
  }
  cout << endl;
  return 0;
  return 0;
}
