#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cctype>
#include<math.h>
#include<string>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
#include<utility>
#include<set>
#include<map>
#include<stdlib.h>
#include<iomanip>

using namespace std;

#define ll long long
#define ld long double
#define EPS 0.0000000001
#define INF 1e9
#define LINF (ll)INF*INF
#define MOD 1000000007
#define rep(i,n) for(int i=0;i<(n);i++)
#define loop(i,a,n) for(int i=a;i<(n);i++)
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)

#define int ll //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int,int> pii;
typedef vector<pii> vp;

int gcd(int a, int b){
    if(b==0) return a;
    return gcd(b,a%b);
}
int lcm(int a, int b){
    return a*b/gcd(a,b);
}


signed main(void) {
    int a,b;
    cin >> a >> b;
    int ma = 100005;
    vi p(ma),prime;
    loop(i,2,ma)if(p[i] == 0){
        prime.push_back(i);
        for(int j = 1; i*j < ma; j++)if(p[i*j] == 0)p[i*j] = i;
    }
    for(int i = prime.size()-1; i >= 0; i--)if(prime[i]*prime[i] <= b){
        for(int j = b/prime[i]; j >= prime[i] && prime[i]*j >= a; j--){
            bool c = true;
            int t = prime[i]*j;
            rep(k,i)if(t % prime[k] == 0)c = false;
            if(c){
                cout << t << endl;
                return 0;
            }
        }
    }
}