#define _USE_MATH_DEFINES
#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define MT make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define RT return
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;

vector<vector<int>> divisorsAll(int n) {
    vector<vector<int>> res(n + 1);
    for (int i = 1; i <= n; ++i) {
        for (int j = i; j <= n; j += i) {
            res[j].push_back(i);
        }
    }
    return res;
}

template<class Val>
map<Val, int> factorize(Val n) {
    map<Val, int> res;
    for (Val i = 2; (long long)i*i <= n; ++i) {
        while (n%i == 0) {
            n /= i;
            ++res[i];
        }
    }
    if (n != 1) ++res[n];
    return res;
}

void solve() {
	// 約数列挙するだけ
    int N, K;
    cin >> N >> K;

    // (約数の個数, -解候補)
    pii ans(0, 0);
    auto D = divisorsAll(N);
    auto F = factorize(N);

    for (int i = 1; i < N; ++i) {
        int n = i;
        int common = 0;
        each(p, F) {
            rep(j, p.second) {
                if (n%p.first == 0) {
                    common++;
                    n /= p.first;
                }
            }
        }
        if (common >= K) {
            smax(ans, pii(sz(D[i]), -i));
        }
    }
    
    cout << -ans.second << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}