#include "bits/stdc++.h"
#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 1000000007;

vector<bool>isPrime;
void Sieve(int N) {
	if (N + 10 > isPrime.size())isPrime.resize(N + 10, true);
	isPrime[0] = false; isPrime[1] = false;
	for (int i = 2; i * i <= N; i++) {
		if (isPrime[i]) {
			for (int j = 2; i * j <= N; j++) {
				isPrime[i * j] = false;
			}
		}
	}
}
bool prime(ll n) {
	if (n == 1)return true;
	for (ll i = 2; i * i <= n; i++) {
		if (n % i == 0)return false;
	}
	return true;
}
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll N; cin >> N;
	Sieve(N);
	vector<int>a;
	for (int i = 2; i <= 1010; i++) {
		if (prime(i)) {
			if (i * i <= N)a.push_back(i * i);
		}
	}
	vector<int>now;
	for (int i = 2; i <= N; i++) {
		if (isPrime[i])now.push_back(i);
	}
	int ans = 0;
	for (int i = 0; i < now.size(); i++) {
		for (int j = 0; j < a.size(); j++) {
			if (isPrime[min(N + 1, max(0LL, j - i))])ans++;
		}
	}
	cout << ans << endl;
	return 0;
}