import sys
input=lambda:sys.stdin.readline().rstrip()
rang=5*10**6
isPrime=[1 for i in range(rang+1)]
isPrime[1]=0
for i in range(2,rang+1):
	if isPrime[i]:
		for j in range(i*2,rang+1,i):
			isPrime[j]=0
N=int(input())
A=list(map(int,input().split()))
target=[0 for i in range(10)]
used=[0 for i in range(10)]
for i in A:
	target[i]=1
K,ans=1,0
for L in range(1,rang+1):
	for i in str(L):
		if isPrime[L]:
			used[int(i)]+=1
	while K<L and any([used[i]>0 and target[i]==0 for i in range(10)]):
		if isPrime[K]:
			for i in str(K):
				used[int(i)]-=1
		K+=1
	if all([(used[i]==0)^target[i] for i in range(10)]):
		ans=max(ans,L-K)
print(ans)