K = int(input())
N = int(input())

def calc(n):
    now = n
    while now >= 10:
        a = str(now)
        now = 0
        for i in a:
            now += int(i)
    return now

def era(n):
    """
    n以下の素数をリストで小さい順に返す。
    O(nlognlogn)
    """
    s = [1 for _ in range(n+1)]
    for i in range(2,n+1):
        if s[i] == 0:
            continue
        j = 2
        while j * i <= n:
            s[j*i] = 0
            j += 1
    l = []
    for i in range(2,n+1):
        if s[i] == 1:
            l.append(i)
    return l

l = era(N)
now = 0
li = []
nn = 0
for i in range(len(l)):
    if l[i] < K:
        continue
    s = set()
    k = 0
    for j in range(10):
        ni = i + j
        k = j
        if ni >= len(l):
            break
        a = calc(l[ni])
        if a in s:
            break
        s.add(a)
    if now <= k:
        now = k
        nn = l[i]
        li = []
        for j in range(now):
            li.append(l[i + j])

print(nn)