#include <bits/stdc++.h>
using namespace std;
struct __s {
  __s() {
    if (1) {
      ios_base::Init i;
      cin.sync_with_stdio(0);
      cin.tie(0);
    }
  }
  ~__s() {
    if (!1)
      fprintf(stderr, "Execution time: %.3lf s.\n",
              (double)clock() / CLOCKS_PER_SEC);
    long long n;
    cin >> n;
  }
} __S;
bool p[2111111];
long long a[1111];
int main(void) {
  p[1] = true;
  for (long long i = 2; i <= 2000000; i++) {
    if (p[i]) continue;
    for (long long j = i * i; j <= 2000000; j += i) {
      p[j] = true;
    }
  }
  long long n;
  cin >> n;
  long long a1 = 0;
  long long a2 = 0;
  for (long long i = 0; i < (long long)(n); i++) {
    cin >> a[i];
    if (a[i] == 1)
      a1++;
    else if (!p[1 + a[i]])
      a2 = a[i];
  }
  if (a1 + !!a2 >= 2) {
    cout << a1 + !!a2 << '\n';
    for (long long i = 0; i < (long long)(a1); i++) cout << 1 << " ";
    if (a2) cout << a2;
    cout << '\n';
    return 0;
  }
  for (long long i = 0; i < (long long)(n); i++) {
    for (long long j = i + 1; j < n; j++) {
      if (!p[a[i] + a[j]]) {
        cout << 2 << '\n';
        cout << a[i] << " " << a[j] << '\n';
        return 0;
      }
    }
  }
  cout << 1 << '\n';
  cout << a[0] << '\n';
  return 0;
}
