#include <bits/stdc++.h>
using namespace std;
const int N = 2 * (1e6) + 2;
bool is_prime[N + 77];
void sieve() {
  memset(is_prime, 1, sizeof is_prime);
  is_prime[0] = is_prime[1] = 0;
  for (int i = 4; i <= N; i += 2) is_prime[i] = 0;
  for (long long i = 3; i <= N; i += 2) {
    if (is_prime[i])
      for (long long j = i * i; j <= N; j += i) {
        is_prime[j] = 0;
      }
  }
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0);
  sieve();
  int n;
  cin >> n;
  vector<int> nums(n);
  int cnt = 0, ex = -1, one = -1;
  for (int i = 0; i < n; i++) {
    cin >> nums[i];
    if (nums[i] == 1) cnt += 1;
    if (nums[i] != 1 && is_prime[nums[i] + 1] && ex == -1) {
      cnt += 1;
      ex = nums[i];
    }
    if (is_prime[nums[i]]) one = nums[i];
  }
  int a = -1, b = -1;
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      if (is_prime[nums[i] + nums[j]]) {
        a = nums[i];
        b = nums[j];
      }
    }
  }
  if (a != -1 && cnt < 2) {
    cout << "2\n";
    cout << a << " " << b << '\n';
  } else if (cnt == 1 && ex == -1) {
    cout << "1\n1\n";
  } else if (cnt >= 2) {
    cout << cnt << '\n';
    for (int i = ex == -1 ? 0 : 1; i < cnt; i++) cout << "1 ";
    if (ex != -1)
      cout << ex << '\n';
    else
      cout << '\n';
  } else if (one != -1) {
    cout << "1\n" << one << '\n';
  } else
    cout << "1\n" << nums[0] << '\n';
  return 0;
}
