#include <bits/stdc++.h>
using namespace std;
int a[2000001];
vector<int> v;
bool prime(int x) {
  for (int i = 2; i * i <= x; ++i) {
    if (x % i == 0) return 0;
  }
  return 1;
}
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    scanf("%d", &a[i]);
  }
  sort(a, a + n);
  bool yes = 0;
  for (int i = 0; i < n; ++i) {
    for (int j = n - 1; j > i; --j) {
      if (prime(a[i] + a[j])) {
        if (a[i] == 1) {
          if (a[j] != 1) v.push_back(a[j]);
          yes = 1;
          break;
        } else {
          puts("2");
          printf("%d %d\n", a[i], a[j]);
          return 0;
        }
      }
    }
    if (yes) break;
  }
  if (yes) {
    for (int i = 0; i < n; ++i) {
      if (a[i] == 1) v.push_back(a[i]);
    }
    printf("%d\n", (int)v.size());
    for (int i = 0; i < v.size(); ++i) printf("%d ", v[i]);
  } else {
    printf("1\n%d", a[0]);
  }
  return 0;
}
