#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for (int i = (int)n - 1; i > -1; i--)
#define all(x) (x).begin(), (x).end()
#define ll long long
#define ld long double
#define INF 1000000000000000000
typedef pair<ll, ll> pll;

int N, K;
pll prime_factorize(long long N) {
    ll res1 = 0, res2 = 1;
    for (long long a = 2; a * a <= N; ++a) {
        if (N % a != 0)
            continue;
        long long ex = 0; // 指数

        // 割れる限り割り続ける
        while (N % a == 0) {
            ++ex;
            N /= a;
        }

        // その結果を push
        res1 += ex;
        res2 *= (ex + 1);
    }

    // 最後に残った数について
    if (N != 1) {
        res1 += 1;
        res2 *= 2;
    }
    return {res1, res2};
}

long long GCD(long long a, long long b) {
    if (b == 0)
        return a;
    else
        return GCD(b, a % b);
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin >> N >> K;
    vector<ll> tmp;
    for (int i = 1; i < N; i++) {
        int gcd = GCD(i, N);
        pll pri = prime_factorize(gcd);
        if (pri.first >= K)
            tmp.push_back(i);
    }

    ll en = 0, ans;
    rep(i, tmp.size()) {
        pll pri = prime_factorize(tmp[i]);
        if (pri.second > en) {
            en = pri.second;
            ans = tmp[i];
        } else if (pri.second == en) {
            if (tmp[i] < ans)
                ans = tmp[i];
        }
    }

    cout << ans << endl;
    return 0;
}