#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <functional>

using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;

#define repi(i,a,b) for(ll i=a;i<b;i++)
#define rep(i,a) repi(i,0,a)
#define rrep(i,a) for(ll i=a-1;i>=0;i--)

void search(ll val, ll n, ll N, ll k, ll K, ll pidx, vector<P> plist, ll* maxval, ll* maxn){
  // printf("val:%lld n:%lld k:%lld p:%lld\n", val, n, k, plist[pidx].first);
  if(pidx == (ll)plist.size()){
    if(k >= K){
      if(val == *maxval) *maxn = min(*maxn, n);
      if(val > *maxval) *maxn = n;
      *maxval = max(*maxval, val);
    }
  }
  else{
    ll powp = 0;
    while(n < N){
      search(val*(powp+1), n, N, k, K, pidx+1, plist, maxval, maxn);
      if(++powp <= plist[pidx].second) k++;
      n *= plist[pidx].first;
    }
  }
}

int main(){
  ll N, K;
  cin >> N >> K;
  ll N_ = N;
  vector<P> plist;
  for(ll i=2; i*i<=N_; i++){
    ll cnt = 0;
    while(N_ % i == 0){
      N_ /= i;
      cnt++;
    }
    if(cnt){
      plist.emplace_back(i, cnt);
    }
  }
  if(N_ > 1) plist.emplace_back(N_, 1);
  ll smallp[] = {2, 3, 5, 7, 11, 13};
  rep(i, 6){
    bool flg = true;
    for(auto it=plist.begin();it<plist.end();++it){
      if(smallp[i] == (*it).first){
        flg = false;
        break;
      }
    }
    if(flg) plist.emplace_back(smallp[i], 0);
  }
  ll maxn = 1, maxval = 0;
  search(1, 1, N, 0, K, 0, plist, &maxval, &maxn);
  cout << maxn << endl;
  return 0;
}