// yukicoder 774 tatyamと素数大富豪
// 2019.5.12 bal4u

#include <stdio.h>
#include <stdlib.h>

typedef long long ll;
typedef unsigned long long ull;

//// ラビン素数テスト
#define mulmod128(a,b,n) ((__int128_t)a*b % n)

ull powmod(ull a, ull k, ull n)
{
	ull bit = 0x2000000000000000LL, p = 1;
	while (bit) {
		if (p > 1) p = mulmod128(p, p, n);
		if (k & bit) p = mulmod128(p, a, n);
		bit >>= 1;
	}
	return p;
}

unsigned xorshift(int id) {
  static unsigned y = 2463534242;
  y = y ^ (y << 13), y = y ^ (y >> 17), y = y ^ (y << 5);
  return y;
}

ull gcd(ull a, ull b) {
	ull r;
	while (b != 0) r = a % b, a = b, b = r;
	return a;
}

int suspect(ull n) {
	int i, j, b;
	ull t, u, x;

	u = n-1, t = 0; while ((u & 1) == 0) u >>= 1, t++;
	for (j = 0; j < 6; j++) {
		do b = xorshift(j) % n;
		while (gcd(b, n) > 1);

		x = powmod(b, u, n);
		if (x == 1 || x == n-1) continue;
		for (i = 1; i < t; i++) {
			x = mulmod128(x, x, n);
			if (x == 1) return 0;
			if (x == n-1) break;
		}
		if (i == t) return 0;
	}
	return 1;
}

int miller_rabin(ull n) {
	if (n <= 1) return 0;
	if (n == 2 || n == 3) return 1;
	if ((n & 1) == 0) return 0;
	return suspect(n);
}

int a[15], w[15], n;
ll tbl[363000]; int sz;

// Kの数{ 1,2,3,4,5,6,7,8,9 } の順列を生成する K!個
void genperm(int K) {
	int k, t;
	char c[12], *pc, *q;
	static char p[12] = { 1,1,1,1,1,1,1,1,1 };

	q = p, pc = c, k = 1;
	while (k <= K) *q++ = *pc++ = k++;  // 1 2 3 のように１から
	k = 1, pc = c;
	do {
		t = *(p + k);
		*(p + k) = *(q = p + ((k & 1) ? *pc : 0));
		*q = t;
{		
	int i, _a;
	long long x;
	x = 0; for (i = 0; i < K; i++)
		_a = p[i], x = x * w[_a] + a[_a];
	tbl[sz++] = x;
}
//		showperm(p);
		
		k = 1, pc = c;
		while (*pc == 0) *pc++ = k++;
		(*pc)--;
	} while (k < K);
}

int cmp(const void *a, const void *b) {
	ll t = *(ll *)b - *(ll *)a;
	if (t < 0) return -1;
	return t >= 0;
}

int main()
{
	int i;
	long long ans, pre;
	scanf("%d", &n);
	for (i = 1; i <= n; i++) {
		scanf("%d", a+i);
		w[i] = a[i] < 10? 10: 100;
	}
	genperm(n);

	qsort(tbl, sz, sizeof(ll), cmp);
	ans = pre = -1LL; for (i = 0; i < sz; i++) if (tbl[i] != pre) {
		if (miller_rabin(tbl[i])) { ans = tbl[i]; break; }
		pre = tbl[i];
	}
	printf("%lld\n", ans);
	return 0;
}