#include <bits/stdc++.h>

using namespace std;

vector <long long int> prime;
bool isprime[500001];

void eratos(void)
{
	memset(isprime, true, sizeof(isprime));

	for (int j = 2; j <= 500000; j++)
	{
		if (isprime[j])
		{
			prime.push_back(j);
			for (int k = 2 * j; k <= 500000; k += j)
			{
				isprime[k] = false;
			}
		}
	}
}
int main(void)
{
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	eratos();
	vector <long long int> vec;
	long long int n;
	
	cin >> n;

	for (auto p : prime)
	{
		if (p * p > n) break;
		vec.push_back(p * p);
	}

	int res = 0;

	for (int i = 0; i < vec.size(); i++)
	{
		for (int j = 0; j < prime.size(); j++)
		{
			if (prime[j] > n) break;
			long long int c = vec[i] - prime[j];
			if (c <= 1) break;
			if (isprime[c] && c<=n) res++;
		}
	}
	
	cout << res << '\n';
	return 0;
}