#include <bits/stdc++.h>
using namespace std;
const int maxn = 1234;
int n, a[maxn], freq[1000007], prime[2000007];
void siev() {
  for (int i = 2; i * i <= 2000005; i++) {
    if (!prime[i]) continue;
    for (int j = i + i; j <= 2000005; j += i) {
      prime[j] = false;
    }
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  for (int i = 0; i < 2000007; i++) prime[i] = true;
  siev();
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    freq[a[i]]++;
  }
  if (freq[1] > 1) {
    for (int i = 0; i < n; i++)
      if (prime[a[i] + 1] && a[i] != 1) {
        cout << freq[1] + 1 << '\n';
        for (int j = 0; j < freq[1]; j++) cout << 1 << " ";
        cout << a[i];
        return 0;
      }
    cout << freq[1] << '\n';
    for (int j = 0; j < freq[1]; j++) cout << 1 << " ";
    return 0;
  }
  for (int i = 0; i < n; i++)
    for (int j = i + 1; j < n; j++)
      if (prime[a[i] + a[j]]) {
        cout << 2 << '\n' << a[i] << " " << a[j];
        return 0;
      }
  cout << 1 << '\n' << a[0];
  return 0;
}
