#include <bits/stdc++.h>
using namespace std;
bool prime_check(long long num) {
  if (num < 2) return 0;
  if (num % 2 == 0 && num != 2) return 0;
  for (int i = 3; i * i <= num; i++) {
    if (num % i == 0) return 0;
  }
  return 1;
}
void solve() {
  int n;
  cin >> n;
  int ctr = 0;
  int x;
  set<int> ev, od;
  for (int i = 0; i < n; i++) {
    scanf("%d", &x);
    if (x == 1) {
      ctr++;
    }
    if (x & 1) {
      od.insert(x);
    } else {
      ev.insert(x);
    }
  }
  if (ctr) {
    int f = (ctr > 1);
    int x = 0;
    for (auto v : ev) {
      if (prime_check(1 + v)) {
        x = v;
        f = 1;
        break;
      }
    }
    if (ev.find(2) != ev.end()) {
      x = 2;
      f = 1;
    }
    if (f) {
      cout << ctr + (x != 0) << endl;
      for (int i = 0; i < ctr; i++) {
        cout << "1 ";
      }
      if (x) {
        cout << x;
      }
      cout << endl;
      return;
    }
  }
  for (auto u : od) {
    for (auto v : ev) {
      if (prime_check(u + v)) {
        cout << 2 << endl;
        cout << u << " " << v << endl;
        return;
      }
    }
  }
  cout << 1 << endl << x << endl;
}
int main(int argc, const char **argv) {
  if (argc >= 2) {
    freopen(argv[1], "r", stdin);
  }
  solve();
}
