package main

import (
	"fmt"
	"sort"
)

func main() {
	var K, N int
	fmt.Scan(&K, &N)
	pl := Sieve(K, N)
	sort.Ints(pl)
	hashList := make([]int, len(pl))
	for i, m := range pl {
		hashList[i] = hash(m)
	}
	ans := 0
	ans_len := 0
	for i := 0; i < len(hashList); i++ {
		numMap := make(map[int]int)
		numMap[hashList[i]] = 1
		for j := i + 1; j < len(hashList); j++ {
			numMap[hashList[j-1]] = 1
			_, flag := numMap[hashList[j]]
			//fmt.Println(len(numMap))
			if !flag {
				if j-i+1 > ans_len {
					ans = pl[i]
					ans_len = j - i + 1
				} else if j-i+1 == ans_len {
					ans = max(ans, pl[i])
				}
			} else {
				break
			}
		}
	}
	fmt.Println(ans)
}

func hash(m int) int {
	for m >= 10 {
		n := m
		m = 0
		for n > 0 {
			m += n % 10
			n /= 10
		}
	}
	return m
}


func Sieve(k, n int) []int {
	isNotPrime := make([]bool, n+1)
	primeList := make([]int, 0)
	isNotPrime[0] = true
	isNotPrime[1] = true
	for i := 2; i <= n; i++ {
		if !isNotPrime[i] { // 素数の場合
			if i >= k {
				primeList = append(primeList, i)
			}
			for j := 2 * i; j <= n; j += i {
				isNotPrime[j] = true
			}
		}
	}
	return primeList
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}