#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("inline")
#include<bits/stdc++.h>
using namespace std;
template<class T> struct cLtraits_identity{
  using type = T;
}
;
template<class T> using cLtraits_try_make_signed =
  typename conditional<
    is_integral<T>::value,
    make_signed<T>,
    cLtraits_identity<T>
    >::type;
template <class S, class T> struct cLtraits_common_type{
  using tS = typename cLtraits_try_make_signed<S>::type;
  using tT = typename cLtraits_try_make_signed<T>::type;
  using type = typename common_type<tS,tT>::type;
}
;
void*wmem;
char memarr[96000000];
template<class S, class T> inline auto min_L(S a, T b)
-> typename cLtraits_common_type<S,T>::type{
  return (typename cLtraits_common_type<S,T>::type) a <= (typename cLtraits_common_type<S,T>::type) b ? a : b;
}
template<class S, class T> inline auto max_L(S a, T b)
-> typename cLtraits_common_type<S,T>::type{
  return (typename cLtraits_common_type<S,T>::type) a >= (typename cLtraits_common_type<S,T>::type) b ? a : b;
}
template<class T> inline void walloc1d(T **arr, int x, void **mem = &wmem){
  static int skip[16] = {0, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
  (*mem) = (void*)( ((char*)(*mem)) + skip[((unsigned long long)(*mem)) & 15] );
  (*arr)=(T*)(*mem);
  (*mem)=((*arr)+x);
}
template<class T> inline void walloc1d(T **arr, int x1, int x2, void **mem = &wmem){
  walloc1d(arr, x2-x1, mem);
  (*arr) -= x1;
}
inline int my_getchar_unlocked(){
  static char buf[1048576];
  static int s = 1048576;
  static int e = 1048576;
  if(s == e && e == 1048576){
    e = fread_unlocked(buf, 1, 1048576, stdin);
    s = 0;
  }
  if(s == e){
    return EOF;
  }
  return buf[s++];
}
inline void rd(long long &x){
  int k;
  int m=0;
  x=0;
  for(;;){
    k = my_getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = my_getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
struct MY_WRITER{
  char buf[1048576];
  int s;
  int e;
  MY_WRITER(){
    s = 0;
    e = 1048576;
  }
  ~MY_WRITER(){
    if(s){
      fwrite_unlocked(buf, 1, s, stdout);
    }
  }
}
;
MY_WRITER MY_WRITER_VAR;
void my_putchar_unlocked(int a){
  if(MY_WRITER_VAR.s == MY_WRITER_VAR.e){
    fwrite_unlocked(MY_WRITER_VAR.buf, 1, MY_WRITER_VAR.s, stdout);
    MY_WRITER_VAR.s = 0;
  }
  MY_WRITER_VAR.buf[MY_WRITER_VAR.s++] = a;
}
inline void wt_L(char a){
  my_putchar_unlocked(a);
}
inline void wt_L(int x){
  int s=0;
  int m=0;
  char f[10];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    my_putchar_unlocked('-');
  }
  while(s--){
    my_putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(unsigned x){
  int s=0;
  char f[10];
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  while(s--){
    my_putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(long long x){
  int s=0;
  int m=0;
  char f[20];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    my_putchar_unlocked('-');
  }
  while(s--){
    my_putchar_unlocked(f[s]+'0');
  }
}
inline void wt_L(unsigned long long x){
  int s=0;
  char f[21];
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  while(s--){
    my_putchar_unlocked(f[s]+'0');
  }
}
int WRITER_DOUBLE_DIGIT = 15;
inline int writerDigit_double(){
  return WRITER_DOUBLE_DIGIT;
}
inline void writerDigit_double(int d){
  WRITER_DOUBLE_DIGIT = d;
}
inline void wt_L(double x){
  const int d = WRITER_DOUBLE_DIGIT;
  int k;
  int r;
  double v;
  if(x!=x || (x==x+1 && x==2*x)){
    my_putchar_unlocked('E');
    my_putchar_unlocked('r');
    my_putchar_unlocked('r');
    return;
  }
  if(x < 0){
    my_putchar_unlocked('-');
    x = -x;
  }
  x += 0.5 * pow(0.1, d);
  r = 0;
  v = 1;
  while(x >= 10*v){
    v *= 10;
    r++;
  }
  while(r >= 0){
    r--;
    k = floor(x / v);
    if(k >= 10){
      k = 9;
    }
    if(k <= -1){
      k = 0;
    }
    x -= k * v;
    v *= 0.1;
    my_putchar_unlocked(k + '0');
  }
  if(d > 0){
    my_putchar_unlocked('.');
    v = 1;
    for(r=(0);r<(d);r++){
      v *= 0.1;
      k = floor(x / v);
      if(k >= 10){
        k = 9;
      }
      if(k <= -1){
        k = 0;
      }
      x -= k * v;
      my_putchar_unlocked(k + '0');
    }
  }
}
inline void wt_L(const char c[]){
  int i=0;
  for(i=0;c[i]!='\0';i++){
    my_putchar_unlocked(c[i]);
  }
}
inline void wt_L(string &x){
  int i=0;
  for(i=0;x[i]!='\0';i++){
    my_putchar_unlocked(x[i]);
  }
}
int Prime_L(int N, int res[], void *mem=wmem){
  int i;
  int a;
  int b;
  int sz = 1;
  const int r = 23000;
  bool*isprime;
  int*sf;
  int ss = 1;
  walloc1d(&isprime, r, &mem);
  walloc1d(&sf, r, &mem);
  N /= 2;
  res[0] = 2;
  b =min_L(r, N);
  for(i=(1);i<(b);i++){
    isprime[i] = 1;
  }
  for(i=(1);i<(b);i++){
    if(isprime[i]){
      res[sz++] = 2*i+1;
      sf[ss] = 2*i*(i+1);
      if(sf[ss] < N){
        while(sf[ss] < r){
          isprime[sf[ss]] = 0;
          sf[ss] += res[ss];
        }
        ss++;
      }
    }
  }
  for(a=r; a<N; a+=r){
    b =min_L(a + r, N);
    isprime -= r;
    for(i=(a);i<(b);i++){
      isprime[i] = 1;
    }
    for(i=(1);i<(ss);i++){
      while(sf[i] < b){
        isprime[sf[i]] = 0;
        sf[i] += res[i];
      }
    }
    for(i=(a);i<(b);i++){
      if(isprime[i]){
        res[sz++] = 2*i+1;
      }
    }
  }
  return sz;
}
template<class T> inline T pow2_L(T a){
  return a*a;
}
template<class S, class T> inline S divup_L(S a, T b){
  return (a+b-1)/b;
}
inline long long Isqrt_s_L(const long long n){
  long long r = sqrt(n);
  r =max_L(r-2, 0);
  while((pow2_L((r+1)))<= n ){
    r++;
  }
  if(r*r!=n){
    r = -1;
  }
  return r;
}
int ps;
int p[2000000];
int arr[2000000];
long long r[2000000];
int main(){
  wmem = memarr;
  long long i;
  long long j;
  long long k;
  long long pp;
  long long L;
  rd(L);
  long long R;
  rd(R);
  ps =Prime_L(2000000,p);
  for(i=(0);i<(R-L+1);i++){
    arr[i] = 1;
  }
  for(i=(0);i<(R-L+1);i++){
    r[i] = L+i;
  }
  for(i=(0);i<(ps);i++){
    pp = p[i];
    k = pp;
    if(k > R){
      break;
    }
    k +=max_L(((divup_L((L - k),pp))), 0)* pp;
    while(k <= R){
      while(r[k-L] % pp == 0){
        r[k-L] /= pp;
      }
      k += pp;
    }
  }
  for(i=(0);i<(R-L+1);i++){
    if(r[i] > 1 &&Isqrt_s_L(r[i])>= 0){
      arr[i] = 0;
    }
  }
  for(i=(0);i<(ps);i++){
    pp = (long long) p[i] * p[i];
    k = pp;
    if(k > R){
      break;
    }
    k +=max_L(((divup_L((L - k),pp))), 0)* pp;
    while(k <= R){
      arr[k-L] = 0;
      k += pp;
    }
  }
  int jZyWAPpY;
  cLtraits_try_make_signed<remove_reference<decltype((*((int*)NULL)))>::type>::type jbtyPBGc;
  if(R-L+1==0){
    jbtyPBGc = 0;
  }
  else{
    jbtyPBGc = arr[0];
    for(jZyWAPpY=(1);jZyWAPpY<(R-L+1);jZyWAPpY++){
      jbtyPBGc += arr[jZyWAPpY];
    }
  }
  wt_L(jbtyPBGc);
  wt_L('\n');
  return 0;
}
// cLay version 20210819-1 [beta]

// --- original code ---
// int ps, p[2d6];
// int arr[2d6]; ll r[2d6];
// {
//   ll i, j, k, pp;
//   ll @L, @R;
//   ps = Prime(2d6,p);
// 
//   rep(i,R-L+1) arr[i] = 1;
//   rep(i,R-L+1) r[i] = L+i;
// 
//   rep(i,ps){
//     pp = p[i];
//     k = pp;
//     if(k > R) break;
//     k += max(((L - k) /+ pp), 0) * pp;
//     while(k <= R){
//       while(r[k-L] % pp == 0) r[k-L] /= pp;
//       k += pp;
//     }
//   }
//   rep(i,R-L+1) if(r[i] > 1 && Isqrt_s(r[i]) >= 0) arr[i] = 0;
// 
//   rep(i,ps){
//     pp = (ll) p[i] * p[i];
//     k = pp;
//     if(k > R) break;
//     k += max(((L - k) /+ pp), 0) * pp;
//     while(k <= R) arr[k-L] = 0, k += pp;
//   }
// 
//   wt(sum(arr(R-L+1)));
// }