import bisect import copy import decimal import fractions import heapq import itertools import math import random import sys from collections import Counter,deque,defaultdict from functools import lru_cache,reduce from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max def _heappush_max(heap,item): heap.append(item) heapq._siftdown_max(heap, 0, len(heap)-1) def _heappushpop_max(heap, item): if heap and item < heap[0]: item, heap[0] = heap[0], item heapq._siftup_max(heap, 0) return item from math import gcd as GCD read=sys.stdin.read readline=sys.stdin.readline readlines=sys.stdin.readlines def Miller_Rabin_Primality_Test(N): if N==1: return False NN=N-1 NN=NN//(NN&-NN) if N<4759123141: lst=[2,7,61] elif N<341550071728321: lst=[2,3,5,7,11,13,17] else: lst=[2,3,5,7,11,13,17,19,23,29,31,37] if N in lst: return True for a in lst: n=NN p=pow(a,n,N) if p==1: continue while p!=N-1: p=p*p%N if p==1 or n==N-1: return False n<<=1 return True N=int(readline()) A=list(readline().split()) se=set() ans=-1 for tpl in itertools.permutations([i for i in range(N)]): P="" for i in tpl: P+=A[i] P=int(P) if P in se: continue se.add(P) if Miller_Rabin_Primality_Test(P): ans=max(ans,P) print(ans)