#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < n; ++i)
#define ALL(c) (c).begin(), (c).end()
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v, x) (std::find(v.begin(), v.end(), x) != v.end())
using namespace std;

using ll = long long;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
const int INF = 1e9;
const long long INFL = 1LL<<60;

vector<bool> create_eratos(int n)
{
  vector<bool> isprime(n+1, 1);
  isprime[0] = 0;
  isprime[1] = 0;

  for (int i = 2; i * i <= n; i++) {
    if (isprime[i]) {
      int j = i + i;
      while (j <= n) {
        isprime[j] = 0;
        j = j + i;
      }
    }
  }
  return isprime;
}

vector<int> createPrimeList(int n)
{
  vector<bool> eratos = create_eratos(n);
  vector<int> result;
  result.reserve(n);
  for (int i = 1; i <=n; i++) {
    if (eratos[i]) {
      result.push_back(i);
    }
  }
  return result;
}

vector<ll> enum_divisor(ll m) {
  vector<ll> divisors;
  for (ll i = 1; i*i <= m; ++i) {
    if (m % i != 0) continue;
    divisors.push_back(i);
    if (i * i != m) divisors.push_back(m / i);
  }
  return divisors;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int l, r;
  cin >> l >> r;
  set<ll> ok;

  for (ll a = l; a < r; a++) {
    if (ok.find(a) != ok.end()) continue;
    int k = 2;
    while (a * k <= r) {
      ok.insert(a * k);
      k++;
    }
  }

/*
  for (ll a = l; a <= r; a++) {
    auto divs = enum_divisor(a);
    for (auto& v : divs) {
      if (l <= v && v <= r && v != a) {
        ok.insert(a);
        break;
      }
    }
  }
*/
  // for (auto itr = ok.begin(); itr != ok.end(); itr++) cerr << *itr << " "; cerr << endl;

  ll ans = r - l;
  ans -= ok.size();
  cout << ans << endl;

  return 0;
}