#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

struct ExtendedSieve{
    vector<int> table;
    const int n;

    ExtendedSieve(int n) : n(n) {
        table.assign(n + 1, 0);
        table[0] = table[1] = 1;
        for(int i = 2; i <= n; ++i){
            if(table[i] > 0)    continue;
            table[i] = i;
            for(int j = i + i; j <= n; j += i){
                if(table[j] == 0)   table[j] = i;
            }
        }
    }

    int operator[](const int& k){
        return table[k];
    }

    bool is_prime(int x){
        if(x < 2)   return false;
        return x == table[x];
    }

    map<int, int> prime_factorization(int x){
        map<int, int> res;
        while(x > 1){
            ++res[table[x]];
            x /= table[x];
        }
        return res;
    }
};

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

    int N, K;
    cin >> N >> K;
    ExtendedSieve sieve(N);
    auto primen = sieve.prime_factorization(N);
    vector<P> cands;
    for(int i = 1; i < N; ++i){
        auto primei = sieve.prime_factorization(i);
        int cnt = 0;
        for(auto [p, c] : primen)   cnt += min(c, primei[p]);
        if(cnt < K) continue;
        cnt = 1;
        for(auto [p, c] : primei)   cnt *= c + 1;
        cands.emplace_back(cnt, i);
    }
    sort(rbegin(cands), rend(cands));
    cout << cands[0].second << endl;

    return 0;
}