#include <bits/stdc++.h>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, a) type a;std::cin>>a;
// VAR(int, x);
#define OUT(d) std::cout<<(d);
#define SP std::cout<<" ";
#define ENDL std::cout<<"\n";
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i,a,b) for (ll i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

using ll = long long;

ll PrimeFactMin(ll n){
	double sqrtn = std::sqrt(n);
	for(ll i=2; i<=sqrtn; ++i){
		int divCount = 0;
		if(n%i == 0){
			do{
				++divCount;
				n/=i;
			}while(n%i == 0);
		    return i;
		}
	}
    return n;
}

int main(){
    INIT;
    VAR(ll, l);VAR(ll, h);
    ll ans = -1;
    ll primeMin = -1;
    int below = std::max(static_cast<ll>(std::sqrt(h)), l);
    FOR(i, below, h+1){
        ll t = PrimeFactMin(i);
        if(i!=t && primeMin<=t){
            primeMin = t;
            ans = i;
        }
        //OUT(i)SP OUT(t)ENDL;
    }
    OUT(ans)ENDL;
    return 0;
}