using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using SB = System.Text.StringBuilder;
//using System.Threading.Tasks;
//using System.Text.RegularExpressions;
//using System.Globalization;
//using System.Diagnostics;
using static System.Console;
using System.Numerics;
using static System.Math;
using pair = Pair<int, int>;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    readonly Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 }; //→↓←↑
    readonly int mod = 1000000007;
    readonly int dom = 998244353;
    bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (b.CompareTo(a) < 0) { a = b; return true; } return false; }

    long gcd(long a, long b)
    {
        return (b != 0) ? gcd(b, a % b) : a;
    }
    long lcm(long a, long b)
    {
        return a / gcd(a, b) * b;
    }
    //ax + by = gcd(a, b)となるx, yを求める
    long extgcd(long a, long b, out long x, out long y)
    {
        long g = a;
        if (b != 0)
        {
            g = extgcd(b, a % b, out y, out x);
            y -= (a / b) * x;
        }
        else
        {
            x = 1;
            y = 0;
        }
        return g;
    }
    void solve()
    {
        int N = cin.nextint;
        int K = cin.nextint;

        int sum = 0;
        int ans = 0;

        for (int j = 2; j < N; j++)
        {
            //WriteLine(j);
            var g = gcd(j, N);
            int cnt = 0;
            var T = g;
            for (int i = 2; i * i <= T; i++)
            {
                while (T % i == 0)
                {
                    cnt++;
                    T /= i;
                }
            }
            if (T != 1)
            {
                cnt++;
            }

            //WriteLine(j + " " + cnt);

            if (cnt >= K)
            {
                var D = new HashMap<int, int>();

                int P = j;
                for (int i = 2; i * i <= P; i++)
                {
                    while (P % i == 0)
                    {
                        D[i]++;
                        P /= i;
                    }
                }
                if (P != 1)
                {
                    D[P]++;
                }

                int tmp = 1;
                foreach (var item in D.Values)
                {
                    tmp *= item + 1;
                }
                if (chmax(ref sum, tmp))
                {
                    ans = j;
                }
            }

        }




        WriteLine(ans);
    }

}

class HashMap<TKey, TValue> : Dictionary<TKey, TValue>
{
    public new TValue this[TKey key]
    {
        get
        {
            TValue value;
            return TryGetValue(key, out value) ? value : default(TValue);
        }
        set
        {
            base[key] = value;
        }
    }
}


static class Ex
{
    public static void join<T>(this IEnumerable<T> values, string sep = " ") => WriteLine(string.Join(sep, values));
    public static string concat<T>(this IEnumerable<T> values) => string.Concat(values);
    public static string reverse(this string s) { var t = s.ToCharArray(); Array.Reverse(t); return t.concat(); }

    public static int lower_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) < 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
    public static int upper_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) <= 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
}

class Pair<T, U> : IComparable<Pair<T, U>> where T : IComparable<T> where U : IComparable<U>
{
    public T f; public U s;
    public Pair(T f, U s) { this.f = f; this.s = s; }
    public int CompareTo(Pair<T, U> a) => f.CompareTo(a.f) != 0 ? f.CompareTo(a.f) : s.CompareTo(a.s);
    public override string ToString() => $"{f} {s}";
}

class Scanner
{
    string[] s; int i;
    readonly char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan => ReadLine().Split();
    public int[] scanint => Array.ConvertAll(scan, int.Parse);
    public long[] scanlong => Array.ConvertAll(scan, long.Parse);
    public double[] scandouble => Array.ConvertAll(scan, double.Parse);
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint => int.Parse(next);
    public long nextlong => long.Parse(next);
    public double nextdouble => double.Parse(next);
}