#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef complex<double> P;
typedef pair<int,int> pii;
#define REP(i,n) for(ll i=0;i<n;++i)
#define REPR(i,n) for(ll i=1;i<n;++i)
#define FOR(i,a,b) for(ll i=a;i<b;++i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define MOD (ll)(1e9+7)
#define ADD(a,b) a=((a)+(b))%MOD
#define FIX(a) ((a)%MOD+MOD)%MOD

ll L,H;
bool isp[125252];
vl ps;

int main(){
  scanf("%lld%lld",&L,&H);
  REP(i,125252)isp[i]=true;
  isp[0]=isp[1]=false;
  FOR(x,2,125252){
    if(!isp[x])continue;
    ps.push_back(x);
    {
      int it = x+x;
      while(it<125252){
        isp[it]=false;
        it+=x;
      }
    }
  }
  ll ans = 1;
  ll mxmn = 1;
  REP(i,ps.size()){
    ll x = ps[ps.size()-1-i];
    if(x<mxmn)break;
    ll ub = H/x;
    {
      int id = upper_bound(ALL(ps),ub)-ps.begin();
      if(id>0){
        ll p = ps[id-1];
        if(p*x>=L){
          ll fct = min(p,x);
          if(fct>mxmn || (fct==mxmn&&p*x>ans)){
            ans = p*x;
            mxmn = fct;
            continue;
          }
        }
      }
    }
    while(ub*x>=L && ub>1){
      ll mfct=x;
      if(ub<125252 && isp[ub]){
        mfct = min(mfct,ub);
      }else{
        REP(j,ps.size()){
          if(ub%ps[j]==0){
            mfct=min(mfct,ps[j]);
            break;
          }
        }
      }
      if(mfct>mxmn || (mfct==mxmn&&ub*x>ans)){
        ans = ub*x;
        mxmn = mfct;
        if(mfct==x)break;
      }
      --ub;
    }
  }
  printf("%lld\n",ans);
  return 0;
}