#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"
#define NDEBUG
#define SHOW(...) static_cast<void>(0)
//!===========================================================!//
//!  dP     dP                          dP                    !//
//!  88     88                          88                    !//
//!  88aaaaa88a .d8888b. .d8888b. .d888b88 .d8888b. 88d888b.  !//
//!  88     88  88ooood8 88'  '88 88'  '88 88ooood8 88'  '88  !//
//!  88     88  88.  ... 88.  .88 88.  .88 88.  ... 88        !//
//!  dP     dP  '88888P' '88888P8 '88888P8 '88888P' dP        !//
//!===========================================================!//
template <typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template <typename T>
std::vector<T> readVec(const std::size_t l)
{
    std::vector<T> v(l);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
using ld = long double;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr unsigned int MOD = 1000000007;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 4;
template <typename F>
constexpr F PI = static_cast<F>(3.1415926535897932385);
std::mt19937 mt{std::random_device{}()};
template <typename T>
bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template <typename T>
bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
template <typename T>
std::vector<T> Vec(const std::size_t n, T v) { return std::vector<T>(n, v); }
template <class... Args>
auto Vec(const std::size_t n, Args... args) { return std::vector<decltype(Vec(args...))>(n, Vec(args...)); }
template <typename T>
constexpr T popCount(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : (T)__builtin_popcountll(u);
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = (v & 0x5555555555555555ULL) + (v >> 1 & 0x5555555555555555ULL), v = (v & 0x3333333333333333ULL) + (v >> 2 & 0x3333333333333333ULL), v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL, static_cast<T>(v * 0x0101010101010101ULL >> 56 & 0x7f);
#endif
}
template <typename T>
constexpr T log2p1(const T u)
{
#ifdef __has_builtin
    return u == 0 ? T(0) : T(64 - __builtin_clzll(u));
#else
    unsigned long long v = static_cast<unsigned long long>(u);
    return v = static_cast<unsigned long long>(v), v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), popCount(v);
#endif
}
template <typename T>
constexpr T clog(const T v) { return v == 0 ? T(0) : log2p1(v - 1); }
template <typename T>
constexpr T msbp1(const T v) { return log2p1(v); }
template <typename T>
constexpr T lsbp1(const T v)
{
#ifdef __has_builtin
    return __builtin_ffsll(v);
#else
    return v == 0 ? T(0) : popCount((v & (-v)) - T(1)) + T(1);
#endif
}
template <typename T>
constexpr bool ispow2(const T v) { return popCount(v) == 1; }
template <typename T>
constexpr T ceil2(const T v) { return v == 0 ? T(1) : T(1) << log2p1(v - 1); }
template <typename T>
constexpr T floor2(const T v) { return v == 0 ? T(0) : T(1) << (log2p1(v) - 1); }
//!=============================================================!//
//!  dP              888888ba           oo                      !//
//!  88              88    '8b                                  !//
//!  88 .d8888b.    a88aaaa8P' 88d888b. dP 88d8b.d8b. .d8888b.  !//
//!  88 Y8ooooo.     88        88'  '88 88 88''88''88 88ooood8  !//
//!  88       88     88        88       88 88  88  88 88.  ...  !//
//!  dP '88888P'     dP        dP       dP dP  dP  dP '88888P'  !//
//!=============================================================!//
template <typename T>
bool isPrime(const T n)
{
    if (n == 1) { return true; }
    for (T i = 2; i * i <= n; i++) {
        if (n % i == 0) { return false; }
    }
    return true;
}
//!=======================================================================================!//
//!   888888ba           oo                        d888888P         dP       dP           !//
//!   88    '8b                                       88            88       88           !//
//!  a88aaaa8P' 88d888b. dP 88d8b.d8b. .d8888b.       88   .d8888b. 88d888b. 88 .d8888b.  !//
//!   88        88'  '88 88 88''88''88 88ooood8       88   88'  '88 88'  '88 88 88ooood8  !//
//!   88        88       88 88  88  88 88.  ...       88   88.  .88 88.  .88 88 88.  ...  !//
//!   dP        dP       dP dP  dP  dP '88888P'       dP   '88888P8 88Y8888' dP '88888P'  !//
//!=======================================================================================!//
std::vector<std::size_t> PrimeTable(const std::size_t max)
{
    std::vector<std::size_t> fact(max + 1);
    std::iota(fact.begin(), fact.end(), 0);
    for (std::size_t i = 2; i <= max; i++) {
        if (fact[i] != i) { continue; }
        for (std::size_t j = 2; i * j <= max; j++) { fact[i * j] = i; }
    }
    return fact;
}
int main()
{
    const int N = read<int>();
    if (N == 1) { return std::cout << 0 << std::endl, 0; }
    const auto isp = PrimeTable(N);
    int ans = 1;
    for (int p = 3; p * p - 2 <= N; p++) {
        if (isp[p] != p) { continue; }
        const ll qq = (ll)p * (ll)p - 2LL;
        if (isPrime(qq)) { ans += 2; }
    }
    std::cout << ans << std::endl;
    return 0;
}