#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9 + 7;
const ll inf = (1 << 30) - 1;
const ll infll = (1LL << 61) - 1;

int n, k, ans;

template <typename T>
T gcd(T a, T b)
{
    return (b == 0 ? a : gcd(b, a % b));
}

template <typename T>
int divisor(T n)
{
    int d = 0;
    for (T i = 1; i * i <= n; i++)
    {
        if (n % i == 0)
        {
            d++;
            if (i * i != n)
                d++;
        }
    }
    return d;
}

template <typename T>
vector<T> prime_factor(T n)
{
    vector<T> res;
    for (T i = 2; i * i <= n; i++)
    {
        while (n % i == 0)
        {
            res.push_back(i);
            n /= i;
        }
    }
    if (n != 1)
        res.push_back(n); //nは素数
    return res;
}

int main()
{
    cin >> n >> k;
    int dm = 0;
    for (int i = 1; i < n; i++)
    {
        int d = divisor(i);
        //cout << d << endl;
        int g = gcd(i, n);
        auto p = prime_factor(g);
        if (p.size() >= k && d > dm)
            dm = d, ans = i;
    }
    cout << ans << endl;
}