#include <bits/stdc++.h>

using namespace std;

bool isprime[1000001];
vector <long long int> prime;
bool check[1000001];
int main(void)
{
	long long int a,b;
	int count = 0;
	//cin.tie(0);
	//ios::sync_with_stdio(false);

	cin >> a >> b;
	
	memset(isprime,true,sizeof(isprime));
	memset(check,false,sizeof(check));
	for(long long int i=2;i<=(long long int)sqrt(b);i++)
	{
		if(isprime[i])
		{
			prime.push_back(i);
			for(long long int j=2*i;j<=(long long int)sqrt(b);j+=i)
			{
				isprime[j]=false;
			}
		}
	}

	for(int i=0;i<prime.size();i++)
	{
		long long int x = prime[i]*prime[i];
		long long int l = ceil((a-1)/x+1)*x;
		for(long long int j=l;j<=b;j+=x)
		{
			if(check[(int)(j-a)]==false)
			{
				check[(int)(j-a)]=true;
				count++;
			}
		}
	}

	cout << (b-a+1) - count << '\n';
	return 0;
}