#include <bits/stdc++.h>
using namespace std;
int const N = 2e6 + 4;
vector<bool> is_prime(N + 5, true);
void seive() {
  is_prime[1] = is_prime[0] = false;
  for (long long i = 2; i <= N; i++) {
    if (is_prime[i]) {
      for (long long j = i * i; j <= N; j += i) is_prime[j] = false;
    }
  }
}
int frq[N];
int main() {
  seive();
  int n;
  cin >> n;
  int a[n];
  vector<int> res1;
  pair<int, int> res2 = {-1, -1};
  int res3 = -1;
  int mx = 0, num = -1;
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < n; i++) {
    if (a[i] == 1) res1.push_back(1);
    if (is_prime[a[i]]) res3 = a[i];
    for (int j = 0; j < n; j++) {
      if (i == j) continue;
      if (is_prime[a[i] + a[j]]) res2 = {a[i], a[j]};
    }
    if (a[i] != 1 && is_prime[a[i] + 1]) {
      num = a[i];
    }
  }
  if (!res1.empty() && num != -1) res1.push_back(num);
  if (res1.empty() && res2.first == -1 && res3 == -1) {
    cout << 1 << endl;
    cout << a[0] << endl;
  } else if (res2.first == -1 || res1.size() > 2) {
    if (res1.empty()) {
      cout << 1 << endl << res3 << endl;
    } else {
      cout << res1.size() << endl;
      for (int ele : res1) cout << ele << " ";
    }
  } else {
    cout << 2 << endl;
    cout << res2.first << " " << res2.second << endl;
  }
}
