def ascan; gets.split.map(&:to_i); end
def scan; gets.to_i; end


require 'prime'


k,n = [gets,gets].map(&:to_i)

# 素数列挙
prime_generator = Prime::EratosthenesGenerator.new
primes = []
begin ; primes << prime_generator.next ; end while primes[-1]<=n


def ash(u)
    u<10 ? u : ash(ash(u/10)+u%10)
end

ptr = 0

while primes[ptr] < k
    ptr+=1
end


li = Array.new(10)
q = []

best = 0
best_head = nil

while ptr < primes.size
    v = primes[ptr]
    h = ash(v)
    while li[h]
        r = q.shift()
        li[r] = nil
    end
    li[h] = v
    q.push(h)
    
    if best <= q.size
        best = q.size
        best_head = li[q[0]]
    end
        
    ptr+=1
end

p best_head