#include "bits/stdc++.h"
using namespace std;
#define rt return
#define FOR(i,j,k) for(int i=j; i<(int)k;++i)
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

vector<int> sieve(int n){
    vector<bool> f(n+1);
    for(int i=3; i<=n; i+=2) f[i] = 1;
    for(int i=3; i<=sqrt(n); i+=2) if(f[i]) for(int j=i*3; j<=n; j+=i) f[j] = 0;
    vector<int> res{2};
    for(int i=3; i<=n; i+=2) if(f[i]) res.push_back(i);
    return res;
}

typedef ll Num;
bool isPrime(Num n){
    if(n==1) return 0;
    for(Num i=2; i*i<=n; ++i)
        if(n%i==0) return 0;
    return 1;
}

ll L, H;

#define LIM 300

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    while(cin >> L >> H){
        auto ps = sieve(100000);
        pair<int, ll> ans(-1, -1);
        if(H - L <= LIM){
            for(ll i = L; i <= H; ++i)if(!isPrime(i)){
                for(ll j = 2; j*j <= i; ++j){
                    if(i%j == 0){
                        smax(ans, mp((int)j, i));
                        break;
                    }
                }
            }
        } else{
            while(ps.back()*2ll > H)ps.pop_back();
            auto ps2 = ps;
            for(int i = sz(ps) - 1; i >= 0;--i){
                while(sz(ps2) && (ll)ps[i] * ps[i] * ps2.back())ps2.pop_back();
                FOR(j, i, sz(ps)){
                    ll val = (ll)ps[i] * ps[j];
                    if(val <= H && val >= L)smax(ans, mp(ps[i], val));
                    if(val > H)break;

                    if(j >= sz(ps2))continue;
                    ll q = H / val;
                    auto it = lower_bound(ps2.begin()+j, ps2.end(), q);
                    if(*it*ps[i] * ps[j] > H && it != ps2.begin())--it;
                    ll val2 = *it*ps[i] * ps[j];
                    if(*it >= ps[j] && val2 >= L && val2 <= H)
                        smax(ans, mp(ps[i], val2));
                }
                if(ans.first != -1)break;
            }
            /*
            rep(i, sz(ps))FOR(j, i, sz(ps)){
                ll val = (ll)ps[i] * ps[j];
                if(val > H)break;
                if(val >= L)
                    smax(ans, mp(ps[i], val));
                
                FOR(k, j, sz(ps)){
                    ll val2 = val*ps[k];
                    if(val2 > H)break;
                    if(val2 >= L)smax(ans, mp(ps[i], val2));

                    FOR(l, k, sz(ps)){
                        ll val3 = val2*ps[l];
                        if(val3 > H)break;
                        if(val3 >= L)smax(ans, mp(ps[i], val3));
                    }
                }
            }*/
        }
        cout << ans.second << endl;
    }
}