#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using namespace std;

using ll=long long;


const int limit=200000;
bool prime[limit+1];

void init(){
	rep(i,limit+1) prime[i]=true;
	prime[0]=prime[1]=false;
	for(ll i=2;i*i<=limit;++i){
		if(prime[i])
			for(ll j=i*i;j<=limit;j+=i)
				prime[j]=false;
	}
	return;
}

int main(void){
	init();
	ll l,h;
	cin >> l >> h;

	ll ans=0LL,fmax=0LL;
	for(ll p=2LL;p*p<=2*h;++p){
		if(prime[p]==false) continue;
		for(ll p2=p; p*p2>=l;--p2){
			if(prime[p2]==false) continue;
			if(p*p2<=h){
				if(fmax < p2 || (fmax == p2  && ans < p*p2)) fmax=p2,ans=p*p2;		
				break;
			}
		}
	}

	if(h-l<=400){
		for(ll i=l;i<=h;++i){
			ll cur=i,res=1LL;
			for(ll f=2LL;f*f<=cur;++f){
				if(prime[f]==false) continue;
				if(cur%f==0){
					cur/=f;
					res=f;
					break;
				}
			}
			if(cur==i) continue;
			if(fmax < res || (fmax == res  && ans < i)) fmax=res,ans=i;		
		}
	}
	cout << ans << endl;
	return 0;
}