require 'prime'

k,n = STDIN.map(&:to_i)
a = []
b = []
max = 0
ans = 0
k.upto(n){|x|
    unless x.prime?
        next
    end
    a.push(x)
    b.push(x % 9)
    tmp = c = 0
    (-1).downto(-9){|i|
        unless b[i]
            break
        end
        if tmp[b[i]] == 0
            tmp |= (1 << b[i])
            c += 1
        else
            break
        end
        }
    if max <= c
        max = c
        ans = a[-c]
    end
    }
p ans