import random
import itertools
def is_prime(q,k=5):
    q=abs(q)
    if q==2 or q==3:return True
    if q==1:return False
    if q%2==0 or q%3==0:return False
    d=(q-1)>>1
    while d&1==0:
        d>>=1
    for i in range(k):
        a=random.randint(1,q-1)
        t=d
        y=pow(a,t,q)
        while t!=q-1 and y!=1 and y!=q-1: 
            y=pow(y,2,q)
            t<<=1
        if y!=q-1 and t&1==0:
            return False
    return True
n=int(input())
a=list(map(int,input().split()))
s=[]
for i in list(itertools.permutations(a)):
    s.append(int(''.join(map(str,i))))
s.sort(reverse=True)
p=0
for i in s:
    if p-i:
        if is_prime(i):
            print(i)
            break
    p=i
else:
    print(-1)