#include <bits/stdc++.h>
using namespace std;
int n, a[1010];
bool is_prime(int num) {
  for (int i = 2; i * i <= num; i++)
    if (num % i == 0) return false;
  return true;
}
int main() {
  scanf("%d", &n);
  int cnt = 0;
  int flag = -1;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    if (a[i] == 1) cnt++;
    if (a[i] != 1 && is_prime(a[i] + 1)) flag = a[i];
  }
  if (cnt && flag != -1 && cnt + 1 > 2) {
    printf("%d\n", cnt + 1);
    while (cnt--) printf("1 ");
    printf("%d\n", flag);
    return 0;
  } else if (cnt >= 2) {
    printf("%d\n", cnt);
    while (cnt--) printf("1 ");
    printf("\n");
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    for (int j = i + 1; j <= n; j++) {
      if (is_prime(a[i] + a[j])) {
        printf("2\n");
        printf("%d %d\n", a[i], a[j]);
        return 0;
      }
    }
  }
  printf("1\n");
  printf("%d\n", a[1]);
  return 0;
}
