#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int mod = 1e9 + 7;
const int inf = (1 << 30) - 1;
const ll infll = (1LL << 61) - 1;

vector<ll> eratosthenes(ll N)
{
    vector<ll> res;
    vector<bool> prime(N + 1, 1);
    prime[0] = prime[1] = false;
    for (ll i = 2; i * i <= N; ++i)
    {
        if (prime[i] == true)
        {
            for (ll j = 2 * i; j <= N; j += i)
            {
                prime[j] = false;
            }
        }
    }
    prime[2] = false;
    for (ll i = 0; i <= N; ++i)
    {
        if (prime[i] == true)
            res.push_back(i);
    }
    return res;
}

template <typename T>
bool is_prime(T N)
{
    if (N < 2)
        return false;
    for (T i = 2; i * i <= N; ++i)
    {
        if (N % i == 0)
            return false;
    }
    return true;
}

ll N, ans;

int main()
{
    cin >> N;
    auto prime = eratosthenes(N);
    int p = prime.size();
    for (int i = 0; i < p && prime[i] * prime[i] - 2 <= N; i++)
    {
        if (is_prime(prime[i] * prime[i] - 2) && prime[i] * prime[i] - 2 <= N)
        {
            ans++;
        }
    }

    ans *= 2;
    if (N >= 2)
        ans++;
    cout << ans << endl;
}