#include <cstdio>
#include <climits>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdio>
#include <climits>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cstring>
#include <set>
#include <map>
#include <complex>
#include <tuple>

#define rep(i, n) for (int i = 0; i < int(n); i++)
using namespace std;
long long MOD = 1000000007;
long long INF = 1000000000000000000; //10^18
typedef long long ll;
typedef unsigned long long ull;


ll powMod(ll x, ll n, ll mod) {
  if (n == 0) return 1;
  ll t = powMod(x, n/2, mod);
  t = t * t % mod;
  if (n & 1) return t * x % mod;
  return t;
}

ll gcd(ll a, ll b) {
  if (a == 0 || b == 0) return a + b;
  if (b > a) return gcd(b, a);
  return gcd(b, a % b);
}

int get_parent(int i, int *parent) {
  while (i != parent[i]) i = parent[i];
  return i;
}

void Union(int i, int j, int *parent, int *rank) {
  i = get_parent(i, parent);
  j = get_parent(j, parent);
  if (i == j) return;
  if (rank[i] < rank[j]) swap(i, j);
  parent[j] = i;
  rank[i] = max(rank[i], rank[j] + 1);
  return;
}

int main(void) {

  int l, r;
  cin >> l >> r;

  int parent[200200], rank[200200] = {};
  for (int i = l; i <= r; i++) parent[i] = i;

  for (int i = l; i <= r; i++) {
    if (get_parent(i, parent) == i) {
      for (int j = 2; i*j <= r; j++) {
	Union(i, i*j, parent, rank);
      }
    }
  }

  set<int> s;
  for (int i = l; i <= r; i++) {
    if (get_parent(i, parent) == i) s.insert(i);
  }

  cout << s.size() - 1 << endl;
}