#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < (t); ++i)
#define dsrep(i,t,s) for(int i = (t)-1; i >= (s); --i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define bn(x) ((1<<(x))-1)
#define newline puts("")
using namespace std;
template<typename T> using vc = vector<T>;
template<typename T> using vv = vc<vc<T>>;
template<typename T> using PQ = priority_queue<T,vc<T>,greater<T> >;
using ll = long long;
using uint = unsigned;
using ull = unsigned long long;
using P = pair<int,int>;
using T3 = tuple<int,int,int>;
using vi = vc<int>;
using vvi = vv<int>;
using vl = vc<ll>;
using vp = vc<P>;
using vt = vc<T3>;
int getInt(){int x;scanf("%d",&x);return x;}
vi pm(int n, int s=0) { vi a(n); iota(rng(a),s); return a;}
template<typename T>istream& operator>>(istream&i,vc<T>&v){rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const T&v,const string& d=""){stringstream s;rep(i,sz(v))(i?s<<d:s)<<v[i];return s.str();}
template<typename T>ostream& operator<<(ostream&o,const vc<T>&v){if(sz(v))o<<join(v," ");return o;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v){return i>>v.fi>>v.se;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,const pair<T1,T2>&v){return o<<v.fi<<","<<v.se;}
vc<string> split(const string& s,char d=' '){vc<string> r(1);for(char c:s)if(c==d)r.pb("");else r.back()+=c;return r;}
string operator*(const string& s,int t){return join(vc<string>(t,s));}
template<typename T1,typename T2>bool mins(T1& x,const T2&y){if(x>y){x=y;return true;}else return false;}
template<typename T1,typename T2>bool maxs(T1& x,const T2&y){if(x<y){x=y;return true;}else return false;}
template<typename T>ll suma(const vc<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
template<typename T>void uni(T& a){sort(rng(a));a.erase(unique(rng(a)),a.end());}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("-1"); return;}
#define yn {puts("Yes");}else{puts("No");}
const int MX = 1000005;
template<typename Tx, typename Ty>Tx dup(Tx x, Ty y){return (x+y-1)/y;}

// linear sieve
vi ps, pf;
void sieve(int mx) {
  pf = vi(mx+1);
  rep(i,mx+1) pf[i] = i;
  for (int i = 2; i <= mx; ++i) {
    if (pf[i] == i) ps.pb(i);
    for (int j = 0; j < sz(ps) && ps[j] <= pf[i]; ++j) {
      int x = ps[j]*i;
      if (x > mx) break;
      pf[x] = ps[j];
    }
  }
}
inline bool isp(int x) { return pf[x] == x && x >= 2;}
vp factor(int x) { // asc
  if (x == 1) return {};
  vp res(1, P(pf[x], 0));
  while (x != 1) {
    if (res.back().fi == pf[x]) res.back().se++;
    else res.pb(P(pf[x],1));
    x /= pf[x];
  }
  return res;
}
//

struct Solver {
  void solve() {
    sieve(MX);
    ll l, r;
    cin>>l>>r;
    ++r;
    int n = r-l;
    vl x(n);
    rep(i,n) x[i] = l+i;
    vi ok(n,1);
    for (int p : ps) {
      for (int j = dup(l,p)*p-l; j < n; j += p) {
        int cnt = 0;
        while (x[j]%p == 0) x[j] /= p, ++cnt;
        if (cnt >= 2) ok[j] = 0;
      }
    }
    int ans = suma(ok);
    cout<<ans<<endl;
  }
};

int main() {
  int ts = 1;
  // scanf("%d",&ts);
  rrep(ti,ts) {
    Solver solver;
    solver.solve();
  }
  return 0;
}