#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
const int MAX=400000;//sqrt(n)よりちょっと大
bitset<MAX> isprime;
void sieve(){
	for(int i=3; i<MAX; i++, i++) isprime[i]=1;
	isprime[2]=1;
	for(int i=3; i<MAX; i++){
		if(isprime[i]){
			for(int j=(i<<1); j<MAX; j+=i) isprime[j]=0;
		}
	}
}
ll p[MAX];
ll n, sq;
int pim;
vector<ll> divs, dsq;
inline ll idx(ll x){
	return (x<=sq)?x-1:(ll)divs.size()-n/x;
}
void calc(){
    sq=0;
    pim=0;
    divs.clear();
    dsq.clear();
    fill(p, p+MAX, 0);

	while((sq+1)*(sq+1)<=n) sq++;
	for(int i=1; i<=sq; i++) divs.push_back(i);
	for(int i=sq; i>=1; i--) divs.push_back(n/i);
	divs.erase(unique(divs.begin(), divs.end()), divs.end());
	dsq.resize(divs.size());
	for(int i=0; i<divs.size(); i++){
		dsq[i]=(ll)sqrt((double)divs[i]);
		while((dsq[i]+1)*(dsq[i]+1)<=divs[i]) dsq[i]++;
	}
	int k=0;
	for(int i=2; i<MAX; i++){
		if(!isprime[i]){
			if(i==sq) pim=k;
			continue;
		}
		p[k]=i;
		k++;
		if(i==sq) pim=k;
	}
}
vector<ll> primecount(){
	vector<ll> dp=divs;
	vector<ll> pis(divs.size(), -1);
	int l;
	for(l=0; divs[l]<p[0]*p[0]; l++){
		if(divs[l]<=1) pis[l]=0;
		else if(divs[l]==2) pis[l]=1;
		else pis[l]=2;
	}
	for(int i=1; i<=pim; i++){
		int r=lower_bound(divs.begin(), divs.end(), p[i]*p[i])-divs.begin();
		for(int j=(int)divs.size()-1; j>=l; j--){
			int k=idx(divs[j]/p[i-1]);
			if(pis[k]!=-1){
				dp[j]-=pis[k]-i+2;
			}else{
				dp[j]-=dp[k];
			}
		}
		for(int j=l; j<r; j++) pis[j]=dp[j]+i-1;
		l=r;
	}
	return pis;
}
int main()
{
    ll l, r; cin>>l>>r;
    sieve();
    auto pi=[&](ll r){
        if(r==0) return 0ll;
        n=r;
        calc();
        auto v=primecount();
        return v.back();
    };
    cout<<pi(r)-pi(l-1)+pi(2*r)-pi(2*l)<<endl;
	return 0;
}