import numpy as np
input()
P=np.arange(M:=5000001)
P[:2]=0
for i in range(M):
	if P[i]:P[2*i::i]=0
S=set();B=set(input())-{" "};L=0;m=1
for i in P:
	L+=1
	if B==S:m=max(L,m)
	if i==0:continue
	if set(str(i))-B:S=set();L=0
	else:S|=set(str(i))
print(m-2)