#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
using VVI = vector<vector<int>>;
using VVL = vector<vector<ll>>;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
#define rep3(i, s, n, d) for (int i = (s); i < (int)(n); i += (d))
#define allpt(v) (v).begin(), (v).end()
#define allpt_c(v) (v).cbegin(), (v).cend()
#define allpt_r(v) (v).rbegin(), (v).rend()

const int mod = 1e9 + 7, mod2 = 998244353;
const ll inf = 1e18;

const string wsp = " ";
const string tb = "\t";
const string rt = "\n";

template <typename T>
void show1dvec(const vector<T> &v)
{
    if (v.size() == 0)
        return;
    int n = v.size() - 1;
    rep(i, n) cout << v[i] << wsp;
    cout << v[n] << rt;
    ;
    return;
}

template <typename T>
void show2dvec(const vector<vector<T>> &v)
{
    int n = v.size();
    rep(i, n) show1dvec(v[i]);
}

template <typename T, typename S>
void show1dpair(const vector<pair<T, S>> &v)
{
    int n = v.size();
    rep(i, n) cout << v[i].first << wsp << v[i].second << rt;
    return;
}

template <typename T, typename S>
void pairzip(const vector<pair<T, S>> &v, vector<T> &t, vector<T> &s)
{
    int n = v.size();
    rep(i, n)
    {
        t.push_back(v[i].first);
        s.push_back(v[i].second);
    }
    return;
}

template <typename T>
void maxvec(vector<T> &v)
{
    T s = v[0];
    int n = v.size();
    rep(i, n - 1)
    {
        if (s > v[i + 1])
        {
            v[i + 1] = s;
        }
        s = v[i + 1];
    }
}

template <typename T, typename S>
bool myfind(T t, S s)
{
    return find(t.cbegin(), t.cend(), s) != t.cend();
}

bool check(int y, int x, int h, int w)
{
    return 0 <= y && y < h && 0 <= x && x < w;
}

VL cumsum(const VL &v)
{
    int s = 0;
    VL ret = {0};

    rep(i, v.size())
    {
        s += v[i];
        ret.push_back(s);
    }
    return ret;
}

bool iskadomatsu(int a, int b, int c)
{
    return (a != b && b != c && c != a) && ((a > b && b < c) || (a < b && b > c));
}

void shave(vector<int> &v, int k, int n)
{
    vector<int> x, y;
    int n_sq = sqrt(n) + 1;
    for (int i = 3; i < n + 1; i += 2)
    {
        x.push_back(i);
    }
    for (int i = 3; i < n_sq; i += 2)
    {
        for (auto itr = x.cbegin(); itr != x.cend(); itr++)
        {
            if (*itr == i || *itr % i != 0)
                y.push_back(*itr);
        }
        x.clear();
        x = y;
        y.clear();
    }

    if (n >= 2 && k <= 2)
        v.push_back(2);
    for (auto itr = x.cbegin(); itr != x.cend(); itr++)
    {
        if (*itr >= k)
            v.push_back(*itr);
    }
}

void hashf(int &x)
{
    while (x >= 10)
    {
        int s = 0;
        while (x > 0)
        {
            s += x % 10;
            x /= 10;
        }
        x = s;
    }
}


int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int k, n;
    cin >> k >> n;
    deque<int> deq, deq_prime;
    VI primes, primes_hashf, ans_list(10, -1);
    shave(primes, k, n);
    primes_hashf = primes;
    for_each(allpt(primes_hashf), hashf);

    vector<bool> num(10, false);

    rep(i, primes.size())
    {
        while (num[primes_hashf[i]] == true)
        {
            num[*deq.cbegin()] = false;
            deq.pop_front();
            deq_prime.pop_front();
        }
        num[primes_hashf[i]] = true;
        deq.push_back(primes_hashf[i]);
        deq_prime.push_back(primes[i]);
        ans_list[deq.size()] = *deq_prime.cbegin();

    }

    reverse(allpt(ans_list));

    rep(i, 10) if (ans_list[i] != -1)
    {
        cout << ans_list[i] << rt;
        break;
    }

    return 0;
}