#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}


//a以下の素数を列挙、計算量:Nlog(log(N))
vector<long long> Eratosthenes(long long a){
    if(a<2) return {};
    vector<long long> p(a+1),ans;
    p[0]=1,p[1]=1;
    long long k=2;
    while(k*k<=a){
        if(p[k]==0){
            ans.push_back(k);
            for(long long i=2;i*k<=a;i++){
                p[i*k]=1;
            }
        }
        k++;
    }
    while(k<=a){
        if(p[k]==0) ans.push_back(k);
        k++;
    }
    return ans;
}

//おちこんだりもしたけれど、私はげんきです。
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	ll L,R;
	cin>>L>>R;
	ll ans=R-L+1;
	ll M=1e6;
	auto er=Eratosthenes(M);
	ll len=R-L+1;
	vector<ll> p(len);
	ans=len;
	rep(i,len) p[i]=i+L;
	for(auto x:er){
		for(int j=(x-L%x)%x;j<len;j+=x){
			if(p[j]==-1) continue;
			if(p[j]%(x*x)==0){
				ans--;
				p[j]=-1;
			}
			else if(p[j]%x==0) p[j]/=x;
		}
	}
	rep(i,len){
		if(p[i]<=M*M) continue;
		ll l=M,r=1e9+1;
		while(r-l>1){
			ll D=(l+r)/2;
			if(D*D<p[i]) l=D;
			else r=D;
		}
		if(r*r==p[i]) ans--;
	}
	cout<<ans<<"\n";
}