#include <bits/stdc++.h>
#define REP_(i, a_, b_, a, b, ...) \
  for (int i = (a), END_##i = (b); i < END_##i; ++i)
#define REP(i, ...) REP_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
#define ALL(x) std::begin(x), std::end(x)
using i64 = long long;

template<typename T, typename U>
inline bool chmax(T &a, U b) {
  return a < b and ((a = std::move(b)), true);
}
template<typename T, typename U>
inline bool chmin(T &a, U b) {
  return a > b and ((a = std::move(b)), true);
}
template<typename T>
inline int ssize(const T &a) {
  return (int) std::size(a);
}

template<typename T>
std::istream &operator>>(std::istream &is, std::vector<T> &a) {
  for (auto &x: a) is >> x;
  return is;
}
template<typename T, typename U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &a) {
  return os << "(" << a.first << ", " << a.second << ")";
}
template<typename Container>
std::ostream &print_seq(const Container &a, std::string_view sep = " ",
                        std::string_view ends = "\n",
                        std::ostream &os = std::cout) {
  auto b = std::begin(a), e = std::end(a);
  for (auto it = std::begin(a); it != e; ++it) {
    if (it != b) os << sep;
    os << *it;
  }
  return os << ends;
}
template<typename T, typename = void>
struct is_iterable : std::false_type {};
template<typename T>
struct is_iterable<T, std::void_t<decltype(std::begin(std::declval<T>())),
                                  decltype(std::end(std::declval<T>()))>>
    : std::true_type {
};

template<typename T, typename = std::enable_if_t<
    is_iterable<T>::value &&
        !std::is_same<T, std::string_view>::value &&
        !std::is_same<T, std::string>::value>>
std::ostream &operator<<(std::ostream &os, const T &a) {
  return print_seq(a, ", ", "", (os << "{")) << "}";
}

void print() { std::cout << "\n"; }
template<class T>
void print(const T &x) {
  std::cout << x << "\n";
}
template<typename Head, typename... Tail>
void print(const Head &head, Tail... tail) {
  std::cout << head << " ";
  print(tail...);
}

struct Input {
  template<typename T>
  operator T() const {
    T x;
    return (std::cin >> x), x;
  }
} in;

#ifdef MY_DEBUG
#include "debug_dump.hpp"
#else
#define DUMP(...)
#endif

using namespace std;

struct PrimeSieve {
  std::vector<int> spf;  // smallest prime factors table.
  std::vector<i64> primes;

  explicit PrimeSieve(int n) : spf(n + 1) {
    // O(n)
    for (int i = 2; i <= n; ++i) {
      if (spf[i] == 0) {
        spf[i] = i;
        primes.push_back(i);
      }
      for (const auto &p: primes) {
        if (i * p > n or p > spf[i]) break;
        spf[i * p] = p;
      }
    }
  }

  inline bool is_prime(int n) const { return spf[n] == n; }
} sieve(1'000'005);

// Returns floor(sqrt(x)).
i64 floor_sqrt(i64 x) {
  assert(x >= 0);
  if (x <= 1) return x;
  i64 r = std::floor(sqrtl((long double) x));
  while (r * r < x) ++r;
  while (r * r > x) --r;
  return r;
}

auto solve() {
  const i64 L = in, R = in;
  const i64 M = R - (L - 1);

  vector<i64> val(M, 0);
  REP(i, M) {
    val[i] = L + i;
  }
  vector<int> has_square(M, 0);
  for (auto p: sieve.primes) {
    for (i64 j = (L + p - 1) / p * p; j <= R; j += p) {
      assert(val[j - L] % p == 0);
      int cnt = 0;
      while (val[j - L] % p == 0) {
        val[j - L] /= p;
        ++cnt;
      }
      if (cnt >= 2) has_square[j - L] = true;
    }
  }
//  DUMP(has_square);
//  DUMP(val);
  int cnt = 0;
  REP(i, M) {
    if (has_square[i]) continue;
    i64 x = floor_sqrt(val[i]);
    if (x != 1 and x * x == val[i]) {
      has_square[i] = true;
      continue;
    }
    ++cnt;
  }
  return cnt;
}

int main() {
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  cout << std::fixed << std::setprecision(15);
  int t = 1;
  REP(test_case, t) {
    auto ans = solve();
    print(ans);
  }
}