import java.util.Arrays;

public class Main {
  private static void solve() {
     int n = ni();
     int[] a = na(n);
    long[] list = new long[500000];
    int ptr = 0;
    while (true) {
      long x = 0;
      for (int v : a) {
        x *= v >= 10 ? 100 : 10;
        x += v;
      }
      list[ptr++] = x;
      if (!nextPermutation(a)) {
        break;
      }
    }
    list = Arrays.copyOf(list, ptr);
    Arrays.sort(list);

    for (int i = ptr - 1; i >= 0; i--) {
      if (doMirrorRabin(list[i])) {
        System.out.println(list[i]);
        return;
      }
    }
    System.out.println(-1);
  }

  public static boolean doMirrorRabin(long n) {
    if (n == 1) return false;
    int[] P = {2, 3, 5, 7, 11, 13, 17, 19, 23}; // n=long
    int s = Long.numberOfTrailingZeros(n - 1);
    long d = n - 1 >> s;
    outer: for (int a : P) {
      if (a >= n)
        continue;

      long mul = a;
      long ad = 1;
      for (long e = d; e > 0; e >>>= 1) {
        if ((e & 1) == 1)
          ad = mul(ad, mul, n);
        mul = mul(mul, mul, n);
      }
      if (ad == 1)
        continue;

      for (int r = 0; r < s; r++) {
        if (ad == n - 1)
          continue outer;
        ad = mul(ad, ad, n);
      }
      return false;
    }
    return true;
  }

  public static long mul(long a, long b, long mod) {
    if (a >= mod || a < 0)
      a %= mod;
    if (a < 0)
      a += mod;
    if (b >= mod || b < 0)
      b %= mod;
    if (b < 0)
      b += mod;

    long ret = 0;
    int x = 63 - Long.numberOfLeadingZeros(b);
    for (; x >= 0; x--) {
      ret += ret;
      if (ret >= mod)
        ret -= mod;
      if (b << ~x < 0) {
        ret += a;
        if (ret >= mod)
          ret -= mod;
      }
    }
    return ret;
  }

  public static boolean nextPermutation(int[] a) {
    int n = a.length;
    int i;
    for (i = n - 2; i >= 0 && a[i] >= a[i + 1]; i--);
    if (i == -1)
      return false;
    int j;
    for (j = i + 1; j < n && a[i] < a[j]; j++);
    int d = a[i];
    a[i] = a[j - 1];
    a[j - 1] = d;
    for (int p = i + 1, q = n - 1; p < q; p++, q--) {
      d = a[p];
      a[p] = a[q];
      a[q] = d;
    }
    return true;
  }


  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}