#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 21;
int main() {
  vector<bool> is_prime(N, true);
  is_prime[0] = is_prime[1] = false;
  for (int i = 2; i * i < N; i++)
    if (is_prime[i])
      for (int j = i * i; j < N; j += i) is_prime[j] = false;
  int n, one = 0;
  scanf("%d", &n);
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
    if (a[i] == 1) one++;
  }
  vector<int> ans(one, 1);
  if (one > 0) {
    for (int i = 0; i < n; i++)
      if (a[i] != 1 && is_prime[a[i] + 1]) {
        ans.push_back(a[i]);
        break;
      }
  }
  if (ans.size() < 2) {
    ans.clear();
    for (int i = 0; ans.size() < 2 && i < n; i++)
      for (int j = i + 1; ans.size() < 2 && j < n; j++)
        if (is_prime[a[i] + a[j]]) {
          ans.push_back(a[i]);
          ans.push_back(a[j]);
        }
  }
  if (ans.empty()) ans.push_back(a[0]);
  printf("%lu\n", ans.size());
  for (int i = ans.size() - 1; i >= 0; i--)
    printf(i == 0 ? "%d\n" : "%d ", ans[i]);
}
