#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
#define rep(i, n) for (lli i = 0; i < (n); i++)
#define rrep(i, n) for (lli i = (n)-1; i >= 0; i--)
using namespace std;

using lli = long long int;
void YESNO(bool), YesNo(bool);
template <class T1, class T2>
bool chmin(T1 &l, const T2 &r);
template <class T1, class T2>
bool chmax(T1 &l, const T2 &r);
struct ufind {
  struct node {
    int par, rank, size;
    void init(int i) {
      par = i;
      rank = 0;
      size = 1;
    }
  };
  vector<node> nodes;
  ufind(int n) {
    nodes.resize(n);
    rep(i, n) nodes[i].init(i);
  }
  int find(int x) {
    return nodes[x].par == x ? x : (nodes[x].par = find(nodes[x].par));
  }
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
      return;
    if (nodes[x].rank < nodes[y].rank) {
      nodes[x].par = y;
      nodes[y].size += nodes[x].size;
    } else {
      nodes[y].par = x;
      if (nodes[x].rank == nodes[y].rank)
        nodes[x].rank++;
      nodes[x].size += nodes[y].size;
    }
  }
  bool same(int x, int y) { return find(x) == find(y); }
  int size(int x) { return nodes[find(x)].size; }
};
int main()
{
  int l, r;
  cin >> l >> r;
  ufind uf(r-l+1);
  
  for(int i = l;i<=r;i++){
    for(int j = i;j<=r;j+=i){
      uf.unite(i-l, j-l);
    }
  }
  set<int> s;
  rep(i, r-l+1){
    s.insert(uf.find(i));
  }
  cout << s.size()-1 <<endl;
}

// -- lib
void YESNO(bool b) { cout << (b ? "YES" : "NO") << endl; }
void YesNo(bool b) { cout << (b ? "Yes" : "No") << endl; }

template <class T1, class T2>
bool chmin(T1 &l, const T2 &r)
{
    return (l > r) ? (l = r, true) : false;
}

template <class T1, class T2>
bool chmax(T1 &l, const T2 &r)
{
    return (l < r) ? (l = r, true) : false;
}