from math import isqrt
import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline

U=5*10**6+1
is_prime=[False]*U
M=isqrt(U)
is_prime[2]=True
for i in range(3,U,2):is_prime[i]=True
for i in range(3,M+1,2):
  if is_prime[i]:
    for j in range(i*i,U,i+i):is_prime[j]=False

primes=[2]
for i in range(3,U,2):
  if is_prime[i]:primes.append(i)

N,*A=map(int,read().split())
ng,ok=[],[]

def make_set(i):
  ret=0
  while i!=0:
    ret|=1<<(i%10)
    i//=10
  return ret

mask=0
for x in A:mask|=1<<x

for p in primes:
  se=make_set(p)
  if ((~mask)&se)!=0:ng.append(p)
  else:ok.append((p,se))

ok.append((U,0));ng.append(U)
ans=-1
l,i=1,0
for x in ng:
  r=x-1
  se=0
  while i<len(ok):
    p,s=ok[i]
    if p>r:break
    se|=s
    i+=1
  
  if se==mask and ans<r-l:ans=r-l
  l=x+1

print(ans)