#include <bits/stdc++.h>

using namespace std;

map <long long int, bool> isprime;
vector <long long int> prime;
map <long long int, bool> check;

int main(void)
{
	long long int a, b;
	int count = 0;
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin >> a >> b;

	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;
}