require'prime'
k=gets.to_i
f=m=z=0
q=[]
Prime.each(gets.to_i){|x|x<k||(f-=1<<q.shift%9while f[x%9]>0
q<<x
f|=1<<x%9
l=q.size
m>l||(m=l;z=q[0]))}
p z