#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using namespace atcoder;
//#pragma GCC optimize("Ofast")
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()

using ll = long long;
using vec = vector<ll>;
using mat = vector<vec>;

ll N,M,H,W,Q,K,A,B;
string S;
using P = pair<ll, ll>;
using tp = tuple<ll, ll, ll>;
const ll INF = (1LL<<60);

template<class T> bool chmin(T &a, const T b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T b){
    if(a < b) {a = b; return true;}
    else return false;
}
template<class T> void my_printv(std::vector<T> v,bool endline = true){
    if(!v.empty()){
        for(std::size_t i{}; i<v.size()-1; ++i) std::cout<<v[i]<<" ";
        std::cout<<v.back();
    }
    if(endline) std::cout<<std::endl;
}

using mint = modint998244353;
using vm = vector<mint>;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll L, R;
    cin>>L>>R;
    ++R;
    bitset<1000000> cop(0), nsf(0);
    vec a(R - L);
    iota(ALL(a), L);
    reps(i, 2, 1000000){
        if(!cop[i]){
            for(int j = i * 2; j < 1000000; j += i) cop[j] = true;
            for(ll x = ((L + i - 1) / i) * i; x < R; x += i){
                if((a[x - L] /= i) % i == 0) nsf[x - L] = true;
            }
        }
    }
    auto is_square = [](ll x) -> bool{
        if(x == 1) return false;
        ll lb = 0, ub = x + 1;
        while(ub - lb > 1){
            ll cen = lb + (ub - lb) / 2;
            if(INF / cen > cen && cen * cen <= x){
                lb = cen;
            }else{
                ub = cen;
            }
        }
        //cout<<x<<' '<<lb * lb<<endl;
        return x == lb * lb;
    };
    rep(i, R - L) {
        if(!nsf[i]) nsf[i] = is_square(a[i]);
    }
    cout<<R - L - nsf.count()<<endl;
    //rep(i, R - L) cout<<L + i<<' '<<nsf[i]<<' '<<a[i]<<endl;
}