#line 1 "prime_util.test.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/843"
#line 2 "/Users/kodamankod/Desktop/CppProcon/Library/proconlib/utility/int_alias.cpp"
#include <cstdint>
#include <cstddef>

using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;
#line 3 "/Users/kodamankod/Desktop/CppProcon/Library/proconlib/utility/rep.cpp"
#include <algorithm>

class rep {
    struct Iter {
        usize itr;
        constexpr Iter(const usize pos) noexcept: itr(pos) { }
        constexpr void operator ++ () noexcept { ++itr; }
        constexpr bool operator != (const Iter& other) const noexcept { return itr != other.itr; }
        constexpr usize operator * () const noexcept { return itr; }
    };
    const Iter first, last;
public:
    explicit constexpr rep(const usize first, const usize last) noexcept: first(first), last(std::max(first, last)) { }
    constexpr Iter begin() const noexcept { return first; }
    constexpr Iter end() const noexcept { return last; }
};
#line 3 "/Users/kodamankod/Desktop/CppProcon/Library/proconlib/bit/ceil_log2.cpp"

constexpr u64 ceil_log2(const u64 x) {
    u64 e = 0;
    while (((u64) 1 << e) < x) ++e;
    return e;
}
#line 4 "/Users/kodamankod/Desktop/CppProcon/Library/proconlib/utility/auto_realloc.cpp"
#include <utility>
#include <vector>

template <class F>
class AutoRealloc {
    using R = typename decltype(std::declval<F>().operator()(std::declval<usize>()))::value_type;
    F func;
    std::vector<R> data;
public:
    explicit AutoRealloc(F&& func): func(std::forward<F>(func)), data() { }
    explicit AutoRealloc(F&& func, const usize capacity): func(std::forward<F>(func)) { reserve(capacity); }
    void reserve(const usize size) {
        if (data.size() < size) {
            const usize pow2 = ((usize) 1 << ceil_log2(size));
            data = func(pow2);
        }
    }
    R operator [] (const usize i) {
        reserve(i + 1);
        return data[i];
    }
};
#line 7 "/Users/kodamankod/Desktop/CppProcon/Library/proconlib/math/prime_util.cpp"
#include <numeric>
#include <cassert>

struct PrimeUtil {
    static inline auto min_prime = AutoRealloc([](const usize n) {
        std::vector<usize> ret(n);
        std::iota(ret.begin(), ret.end(), (usize) 0);
        std::vector<usize> list;
        for (const usize i: rep(2, n)) {
            if (ret[i] == i) list.push_back(i);
            for (const usize p: list) {
                if (p * i >= n || p > ret[i]) break;
                ret[p * i] = p;
            }
        }
        return ret;
    });
    static bool is_prime(const usize n) {
        if (n <= 1) return false;
        return min_prime[n] == n;
    }
    template <class T>
    static std::vector<std::pair<T, usize>> factorize(T x) {
        assert(x > 0);
        std::vector<std::pair<T, usize>> ret;
        while (x != 1) {
            const usize p = min_prime[x];
            ret.emplace_back((T) p, 0);
            while (min_prime[x] == p) {
                ret.back().second++;
                x /= p;
            }
        }
        return ret;
    }
};
#line 5 "prime_util.test.cpp"
#include <iostream>

int main() {
    u32 N;
    std::cin >> N;
    if (N == 1) {
        std::cout << 0 << '\n';
        return 0;
    }
    u32 ans = 1;
    for (const u32 r: rep(3, N + 1)) {
        if (r * r - 2 > N) break;
        if (PrimeUtil::is_prime(r) && PrimeUtil::is_prime(r * r - 2)) {
            ans += 2;
        }
    }
    std::cout << ans << '\n';
    return 0;
}