from collections import Counter
N=int(input())
A=Counter(input().split())

x=5000000

import math 
L=math.floor(math.sqrt(x)) # 平方根を求める

Primelist=[i for i in range(x+1)]
Primelist[1]=0 # 1は素数でないので0にする.
 
for i in Primelist:
    if i>L:
        break
    if i==0:
        continue
    for j in range(2*i,x+1,i):
        Primelist[j]=0

Primes=[0]+[Primelist[j] for j in range(x+1) if Primelist[j]!=0]
P2=[]
for p in Primes:
    P2.append(Counter(str(p)))


S=Counter()

ANS=-1

end=1
for  now in range(1,len(Primes)):
    while set(S)<=set(A):
        if set(S)==set(A):
            if end==348514:
                ANS=max(ANS,5000001-Primes[now-1]-2)
            else:
                ANS=max(ANS,Primes[end]-Primes[now-1]-2)
        if end==348514:
            break
                
        S+=P2[end]
        end+=1
    #print(Primes[now],Primes[end],ANS,A,S)
    S-=P2[now]
    

print(ANS)