#include <bits/stdc++.h>
using namespace std;
using namespace std;
const int maxn = 1000005;
const int mod = 998244353;
bool isp[maxn * 2];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int c1 = 0;
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 2; i < maxn * 2; i++) {
    if (isp[i]) continue;
    for (int j = i * 2; j < maxn * 2; j += i) {
      isp[j] = 1;
    }
  }
  int p = 0;
  for (auto &i : v) {
    cin >> i;
    if (i == 1) {
      c1++;
    }
    if (!isp[i + 1] && i != 1) {
      p = i;
    }
  }
  if (c1 + (p != 0) >= 2) {
    cout << c1 + (p != 0) << '\n';
    for (int i = 0; i < c1; i++) {
      cout << 1 << ' ';
    }
    if (p) cout << p << '\n';
    exit(0);
  }
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      if (!isp[v[i] + v[j]]) {
        cout << 2 << '\n';
        cout << v[i] << ' ' << v[j] << '\n';
        exit(0);
      }
    }
  }
  cout << 1 << '\n';
  cout << v[0] << endl;
}
