#include "bits/stdc++.h"
//#include "atcoder/all"
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
//const bool debug = false;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
//エラトステネスの篩(素数の数を返している)
//11→2,3,5,7,11
vector<long long> sieve(long long  n = 1000000) {
	vector<bool>p(n + 1, true);
	vector<long long>ret;
	p[0] = false;
	p[1] = false;
	for (int i = 2; i <= n; ++i) {
		if (p[i]) {
			ret.push_back(i);
			for (int j = 2 * i; j <= n; j += i) p[j] = false;
		}
	}
	return ret;
}
bool squarefree(long long n) {
	cout << n << endl;
	long long ng = 0;
	long long ok = INF;
	while (1 < abs(ok - ng)) {
		long long c = (ng + ok) / 2;
		if (n <= (c * c)) ok = c;
		else ng = c;
	}
	bool ret = false;
	if (n == ok * ok)ret = true;
	return ret;
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	long long l, r; cin >> l >> r;
	auto p = sieve();
	vector<long long>x(r - l + 1);
	rep(i, x.size()) x[i] = l + i;
	rep(i, p.size()) {
		long long pri = p[i];
		long long fir = ((l + (pri - 1)) / pri) * pri;
		if (r < fir)continue;
		for (; fir <= r; fir += pri) {
			long long idx = fir - l;
			if (0 == (x[idx] % (pri * pri)))x[idx] = 0;
			else if (0 == (x[idx] % pri))x[idx] /= pri;
		}
	}
	int ans = 0;
	rep(i, x.size()) {
		if (0 == x[i])continue;
		else if (1 == x[i])ans++;
		else ans += 1 - squarefree(x[i]);
	}
	cout << ans << endl;
	return 0;
}