#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
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; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 998244353;
constexpr bool debug = false;
//---------------------------------//

std::vector<int> sieve_smallest_prime_factor(int n) {
	assert(n >= 0);
	std::vector<int> res(n + 1);
	std::iota(begin(res), end(res), 0);
	
	for (int i = 2; i * i <= n; ++i) {
		if (res[i] < i) continue;
		for (int j = i * i; j <= n; j += i) {
			if (res[j] == j) res[j] = i;
		}
	}
	
	return res;
}

int main() {
	int N;
	cin >> N;
	auto spf = sieve_smallest_prime_factor(N);
	
	vector<int> cnt(N + 1);
	FOR(i, 1, N + 1) {
		if (i * i > N) break;
		++cnt[i * i];
	}
	REP(i, N) cnt[i + 1] += cnt[i];
	
	ll ans = 0;
	FOR(i, 1, N + 1) {
		ll p = 1; // i * p が平方数となる最小の p
		int prv = -1, o = false;
		for (int cur = i; cur > 1; cur /= spf[cur]) {
			if (prv != spf[cur]) {
				if (o) p *= prv;
				prv = spf[cur];
				o = true;
			}
			else o ^= 1;
		}
		if (o) p *= prv;
		if (p > N) continue;
		
		ans += cnt[N / p];
	}
	cout << ans << endl;
}