/* -*- coding: utf-8 -*-
 *
 * 811.cc:  No.811 約数の個数の最大化 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_P = 1000;

/* typedef */

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vpii;

/* global variables */

bool primes[MAX_P + 1];

/* subroutines */

int gen_primes(int maxp, vi &pnums) {
  memset(primes, true, sizeof(primes));
  primes[0] = primes[1] = false;

  int p;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p]) {
      pnums.push_back(p);
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
    }
  for (; p <= maxp; p++)
    if (primes[p]) pnums.push_back(p);
  return (int)pnums.size();
}

void prime_decomp(int n, vi &pnums, vpii& pds) {
  pds.clear();
  for (vi::iterator vit = pnums.begin();
       vit != pnums.end() && *vit * *vit <= n; vit++) {
    int &pi = *vit, fi = 0;
    while (n % pi == 0) n /= pi, fi++;
    if (fi > 0) pds.push_back(pii(pi, fi));
  }
  if (n > 1) pds.push_back(pii(n, 1));
}

int count_pds(vpii &pds) {
  int c = 0;
  for (vpii::iterator vit = pds.begin(); vit != pds.end(); vit++)
    c += vit->second;
  return c;
}

int count_dvs(vpii &pds) {
  int c = 1;
  for (vpii::iterator vit = pds.begin(); vit != pds.end(); vit++)
    c *= vit->second + 1;
  return c;
}

int gcd(int m, int n) {  // m >= n > 0
  while (n > 0) {
    int r = m % n;
    m = n;
    n = r;
  }
  return m;
}

/* main */

int main() {
  vi pnums;
  int pn = gen_primes(MAX_P, pnums);
  //printf("pn=%d\n", pn);

  int n, k;
  scanf("%d%d", &n, &k);

  vpii npds, mpds;
  prime_decomp(n, pnums, npds);
  int maxm = 0, maxdvc = 0;

  for (int m = 2; m < n; m++) {
    int g = gcd(n, m);
    prime_decomp(g, pnums, mpds);
    if (count_pds(mpds) >= k) {
      prime_decomp(m, pnums, mpds);
      int dvc = count_dvs(mpds);
      if (maxdvc < dvc) maxdvc = dvc, maxm = m;
    }
  }

  printf("%d\n", maxm);
  return 0;
}