//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

constexpr int MAX_N = 100010;

int factrization(LL x) {
    int ret = 0;
    for (LL i = 2; i * i <= x; i++) {
        if (x % i == 0) {
            while (x % i == 0) {
                ret++;
                x /= i;
            }
        }
    }
    if (x != 1)ret++;
    return ret;
}

int divisors(LL x) {
    int ret = 0;
    for (LL i = 1; i * i <= x; i++) {
        if (x % i == 0) {
            ret++;
            if (x / i != i) {
                ret++;
            }
        }
    }
    return ret;
}

LL gcd(LL x, LL y) {
    return y == 0 ? x : gcd(y, x % y);
}

int main() {

    LL N, K;
    cin >> N >> K;

    vector<int> primes(MAX_N);
    for (LL i = 1; i < MAX_N; i++) {
        primes[i] = factrization(i);
    }

    vector<int> divs(MAX_N);
    for (LL i = 1; i < MAX_N; i++) {
        divs[i] = divisors(i);
    }

    LL ans = 1;
    LL maxV = -1;

    for (LL i = 1; i < N; i++) {
        if (primes[gcd(N, i)] >= K) {
            LL d = divs[i];
            if (d > maxV) {
                ans = i;
                maxV = d;
            }
        }
    }

    cout << ans << endl;

    return 0;
}