#include <bits/stdc++.h>
using namespace std;
const long long N = 2e6 + 5;
long long n;
long long a[N], f[N];
long long sieve[N];
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n;
  fill(sieve + 2, sieve + N, 1);
  for (long long i = 2; i < N; i++) {
    for (long long j = 2; i * j < N; j++) sieve[i * j] = 0;
  }
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
    f[a[i]]++;
  }
  long long ans = 0;
  long long ones = f[1];
  if (ones > 0) {
    for (long long i = 3; i < N; i++) {
      if (sieve[i] && f[i - 1]) {
        cout << ones + 1 << "\n";
        for (long long j = 1; j <= ones; j++) cout << 1 << " ";
        cout << i - 1;
        return 0;
      }
    }
    if (ones > 1) {
      cout << ones << "\n";
      for (long long j = 1; j <= ones; j++) cout << 1 << " ";
      return 0;
    }
  }
  for (long long i = 1; i <= n; i++) {
    for (long long j = i + 1; j <= n; j++) {
      if (sieve[a[i] + a[j]]) {
        cout << 2 << "\n";
        cout << a[i] << " " << a[j];
        return 0;
      }
    }
  }
  cout << 1 << "\n";
  cout << a[1];
  return 0;
}
