#ifdef __GNUC__
#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#endif

#define _USE_MATH_DEFINES

#include <iostream>
#include <iomanip>
#include <stdio.h>

#include <sstream>
#include <algorithm>
#include <cmath>

#include <string>
#include <cstring>
#include <vector>
#include <valarray>
#include <array>

#include <queue>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <list>

#include <cassert>//assert();
#include <fstream>
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)

/////////
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
#define PII pair<int,int>
/////////
using namespace::std;

// 最大公約数
template<class T>
inline T gcd(T a, T b){return b == 0 ? a : gcd(b, a % b);}
// 最小公倍数
template<class T>
inline T lcm(T a, T b){return a * b / gcd(a, b);}
////////////////////////////////


inline void solve(){
	LL L,H;
	cin >> L >> H;

	const int MAX_N = 100000;
	vector<int> is_prime(MAX_N + 1,0);
	vector<int> prime;
	prime.reserve(10000);
	is_prime[0] = -1;
	is_prime[1] = 1;
	for(int i=2;i<=MAX_N;++i){
		if( is_prime[i] == 0 ){
			for(int j=i+i;j<=MAX_N;j+=i){
				if( is_prime[j] == 0 ){
					is_prime[j] = i;
				}
			}
			prime.push_back( i );
		}
	}
	
	int primeSize = prime.size();
	LL temp;
	int pos=0;
	for(int i=primeSize-1;i>=0;--i){
		temp = prime[i];
		if( H < temp*temp ) continue;
		else{
			pos = i;
			break;
		}
	}
	if( pos+1 < primeSize ){
		++pos;
	}
	
	LL asd = prime[pos];
	LL ter;
	for(int i=pos;i>=0;--i){
		asd = prime[i];
		ter = (H / prime[i]) * prime[i] ;
		if( ter < L ){
			continue;
		}
		LL ans;
		for(LL num = ter; num >= L; num -= prime[i] ){
			ans = num;
			ter = num / prime[i];
			if( ter < prime[i] ){
				break;
			}
			if( ter == 1 ){//自身が素数
			}else if( ter <= MAX_N ){
				//terが素数で今調べてる素数以上か
				//今調べている素数以上のterの最も小さい約数
				if( (is_prime[ter] == 0 && prime[i] <= ter ) ||
					prime[i] <= is_prime[ter] ){
					cout << ans << endl;
					return;
				}
			}else{
				//prime[i]より小さい素数を調べる
				bool flag = true;
				for(int j = i-1;j>=0;--j){
					if( ter % prime[j] == 0 ){
						flag = false;
						break;
					}
				}
				if( flag ){
					cout << ans << endl;
					return;
				}
			}
		}	
	}
}

signed main(void){
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);
	//std::cout << std::fixed;//小数を10進数表示
	//cout << setprecision(16);//小数をいっぱい表示する。16?

	solve();
}