#include <bits/stdc++.h>
using namespace std;
const int MAXN = 10000;
const int MAXK = 2000010;
bool isPrime[MAXK];
int A[MAXN];
void eratosfen() {
  fill(isPrime, isPrime + MAXK, true);
  for (int i = 2; i < MAXK; i++) {
    if (!isPrime[i]) continue;
    for (int j = i + i; j < MAXK; j += i) isPrime[j] = false;
  }
  isPrime[1] = 0;
  isPrime[0] = 0;
}
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> A[i];
  }
  eratosfen();
  sort(A, A + n);
  int ones = 0;
  int evens = 0;
  for (int i = 0; i < n; ++i) {
    if (A[i] == 1) ones++;
    if (isPrime[A[i] + 1] && A[i] != 1) evens = A[i];
  }
  if (ones + (evens != 0) > 1) {
    cout << ones + (evens != 0) << endl;
    for (int i = 0; i < ones; ++i) cout << 1 << " ";
    if (evens) cout << evens;
    cout << endl;
    return 0;
  }
  for (int i = 0; i < n; ++i)
    for (int j = i + 1; j < n; ++j) {
      if (isPrime[A[i] + A[j]]) {
        cout << 2 << endl;
        cout << A[i] << " " << A[j] << endl;
        return 0;
      }
    }
  cout << 1 << endl;
  cout << A[0] << endl;
  return 0;
}
