#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
vector<long long> sieve(long long  n = 500000) {
	vector<bool>p(n + 1, true);
	vector<long long>ret;
	p[0] = false;
	p[1] = false;
	for (int i = 2; i <= n; ++i) {
		if (!p[i]) continue;
		ret.push_back(i);
		for (int j = 2 * i; j <= n; j += i) p[j] = false;
	}
	return ret;
}
//long long にしているのは p*pとかでこまらないように
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	auto v = sieve(n);
	set<long long>st;
	rep(i, v.size()) {
		st.insert(v[i] * v[i]);
	}
	int ans = 0;
	rep(i, v.size()) {
		if (st.count(v[i] + 2))ans += 2;
	}
	if (1 != n)ans--;
	cout << ans << endl;
	return 0;
}