#include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;

const double PI = 3.1415926535897932384626433832795;
const ll MOD = 1000000007;

const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { -1, 0, 1, 0 };

int gcd(int x, int y) { return y ? gcd(y, x % y) : abs(x); }
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : abs(x); }
int lcm(int x, int y) { return x / gcd(x, y) * y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

vector<bool> sieveOfEratosthenes(int n) {
	vector<bool> isPrime(n + 1, true);
	isPrime[0] = isPrime[1] = false;
	for (int i = 2; i * i <= n; i++) {
		if (!isPrime[i]) {
			continue;
		}

		for (int j = i + i; j <= n; j += i) {
			isPrime[j] = false;
		}
	}

	return isPrime;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	int n;
	cin >> n;

	if (n == 1) {
		cout << 0 << endl;
		return 0;
	}

	vector<bool> isPrime = sieveOfEratosthenes(n);

	// (2, 2, 2)
	int ans = 1;

	for (int p = 3; p <= n; p++) {
		if (!isPrime[p]) {
			continue;
		}

		int r = sqrt(p + 2);
		if (!isPrime[r]) {
			continue;
		}

		if (p + 2 == r * r) {
			ans += 2;
		}
	}

	cout << ans << endl;
	return 0;
}