#include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <cstdio>
#include <cmath>
#include <tuple>
#include <iomanip>
#include <numeric>
#include <unordered_map>
#include <sstream>
#include<limits.h>
#include<float.h>
#include<list>
#include <array>
#include <complex>
#include<stdio.h>
#include<string.h>
#include <bitset>
#include<assert.h>

using namespace std;
#define int long long

#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
#define MOD 1000000007


#define MEM_SIZE 10000
#define DEBUG_OUT true
#define ALL(x) (x).begin(), (x).end()

template<typename T> void DEBUG(T e){if(DEBUG_OUT == false)return; std::cout << e <<" ";}
template<typename T> void DEBUG(const std::vector<T>& v){if(DEBUG_OUT == false)return;for(const auto& e : v){std::cout<< e << " "; } std::cout << std::endl;}
template<typename T> void DEBUG(const std::vector<std::vector<T> >& vv){if(DEBUG_OUT == false)return;for(const auto& v : vv){ DEBUG(v); } }
template<class T,class... Ts> void DEBUG(T d, Ts... e){if(DEBUG_OUT == false)return;DEBUG(d);DEBUG(e...);}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; abort();}}
template< typename T1, typename T2 > inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 > inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

class DisjointSet{
  public:
  vector<int> rank,p;
  DisjointSet(){}
  DisjointSet(int size)
  {
    rank.resize(size,0);
    p.resize(size,0);
    for (int i = 0; i < size; i++)
    {
      makeSet(i);
    }
  }
void makeSet(int x)
{
  p[x] = x;
  rank[x] = 0;
}

bool same(int x, int y)
{
  return findSet(x) == findSet(y);
}

void unite(int x, int y)
{
  link(findSet(x),findSet(y));
}
void link(int x, int y)
{
  if(rank[x] > rank[y])
  {
    p[y] = p[x];
  }
  else
  {
    p[x] = p[y];
  }
  if(rank[x] == rank[y])
  {
    rank[y]++;
  }
}
  int findSet(int x)
  {
    if(x != p[x])
    {
      p[x] = findSet(p[x]);
    }
    return p[x];
  }
};



void solve(void)
{

  int L,R;
  cin>>L>>R;
  DisjointSet DS(R+1);
  for (int x = L; x < R+1; x++)
  {
    int cnt = R/x;
    int add = cnt;
    for (int i = 2; i <= cnt; i++)
    {
      DS.unite(x,i*x);
    }
  }
  set<int> SET;
  for (int i = L; i <= R; i++)
  {
    SET.insert(DS.findSet(i));
  }
  cout<<SET.size()-1<<endl;
  
  
  return;
}
int32_t main(int32_t argc, const char *argv[])
{
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(11);
  solve();

  return 0;
}