#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)
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	long long int a, b;
	int res = 0;

	cin >> a >> b;

	for (long long int i = a; i <= b; i++)
	{
		long long int x = sqrt(i);
		bool ok = true;
		for (long long int j = 2; j <= x; j++)
		{
			if (i % (j * j) == 0)
			{
				ok = false;
				break;
			}
		}
		if (ok)
		{
			res++;
		}
	}

	cout << res << '\n';
	return 0;
}