#include <bits/stdc++.h>
using namespace std;
const int MAXA = 2 * 1000056;
const int MAXN = 1123;
int a[MAXN];
bool sieve[MAXA];
void makeSieve() {
  int i;
  memset(sieve, true, sizeof(sieve));
  sieve[0] = sieve[1] = false;
  int s = sqrt(MAXA);
  for (i = 2; i <= s; i++)
    if (sieve[i]) {
      for (int j = i * i; j < MAXA; j += i) {
        sieve[j] = false;
      }
    }
}
int main() {
  int n, i, cnt, ans, b, ansi, j;
  scanf("%d", &n);
  for (i = 0; i <= n - 1; i++) scanf("%d", &a[i]);
  makeSieve();
  cnt = 0;
  for (i = 0; i <= n - 1; i++)
    if (a[i] == 1) cnt++;
  ans = 0;
  if (cnt > 0) {
    for (i = 0; i <= n - 1; i++)
      if (!((a[i]) & 1)) {
        b = a[i] + 1;
        if (sieve[b]) {
          ans = cnt + 1;
          ansi = a[i];
          break;
        }
      }
    if (ans == 0 && cnt > 1) ans = cnt;
  }
  for (i = 0; i <= n - 2; i++)
    for (j = i + 1; j <= n - 1; j++) {
      b = a[i] + a[j];
      if (sieve[b]) {
        if (2 > ans) {
          printf("2\n");
          printf("%d ", a[i]);
          printf("%d\n", a[j]);
          return 0;
        }
      }
    }
  for (i = 0; i <= n - 1; i++)
    if (sieve[a[i]]) {
      if (1 > ans) {
        printf("1\n");
        printf("%d\n", a[i]);
        return 0;
      }
    }
  if (ans != 0) {
    printf("%d\n", ans);
    if (ans > 0) {
      for (i = 1; i <= cnt; i++) printf("1 ");
      if (ans > cnt)
        printf("%d\n", ansi);
      else
        printf("\n");
    }
  } else {
    ans = 1;
    printf("%d\n", ans);
    printf("%d\n", a[0]);
  }
  return 0;
}
