#include <bits/stdc++.h>
using namespace std;
#define ll long long
 
int main() {
 ios::sync_with_stdio(0);
 cin.tie(0);
 cout.tie(0);
 ll a,b;
 cin>>a>>b;
 ll ans=1;
 if(b>=2*a){
 for(ll i=b;i>=a;i--){
  if(i*2<=b){
    ans=i;
    break;
  }
 }
 cout<<max(ans,(ll)1);
}
else{
  ll ans=1;
  for(ll i=1;i<=b;i++){
    int ans1=b/i-a/i;
    if(a%i==0)ans1++;
    if(ans1>1)ans=max(ans,i);
  }
  cout<<ans;
}
}

#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(ll i=0;i<(ll)n;i++)
#define dump(x)  cerr << "Line " << __LINE__ << ": " <<  #x << " = " << (x) << "\n";
#define spa << " " <<
#define fi first
#define se second
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()

using ld = long double;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;

template<typename T> using V = vector<T>;
template<typename T> using P = pair<T, T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){os << "(" << v.first << ", " << v.second << ")"; return os;}
template<typename T> ostream& operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<vector<T>> &v){ for(auto &e : v){os << e << "\n";} return os;}
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;

template <class T> void UNIQUE(vector<T> &x) {sort(ALL(x));x.erase(unique(ALL(x)), x.end());}
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
void fail() { cout << -1 << '\n'; exit(0); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
template<typename T> void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cerr<<v[i][0];for(ll j=1;j<w;j++)cerr spa v[i][j];cerr<<"\n";}};
template<typename T> void debug(vector<T>&v,ll n){if(n!=0)cerr<<v[0];
for(ll i=1;i<n;i++)cerr spa v[i];
cerr<<"\n";};

const ll INF = (1ll<<62);
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
const ll mod = (int)1e9 + 7;
//const ll mod = 998244353;

bool is_prime(int64_t x) {
  for(int64_t i = 2; i * i <= x; i++) {
    if(x % i == 0) return false;
  }
  return true;
}

int main(){

    ll A, B;
    cin >> A >> B;

    V<ll> primes;
    for(ll i=2;i<=72;i++){
        if(is_prime(i)){
            primes.push_back(i);
        }
    }

    ll sz = primes.size();

    V<ll> dp(1ll<<sz, 0);
    dp[0] = 1;

    for(ll v=A;v<=B;v++){
        ll bit = 0;
        REP(i, sz){
            if(v % primes[i] == 0){
                bit += (1ll<<i);
            }
        }
        V<ll> td(1ll<<sz, 0);
        REP(mask, 1ll<<sz){
            td[mask] += dp[mask];
            if((mask & bit) == 0){
                td[mask | bit] += dp[mask];
            }
        }
        swap(dp, td);
    }

    ll res = 0;
    for(auto x: dp) res += x;
    cout << res << endl;

    // dump(primes)
    // dump(sz)

    return 0;
}