#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}
int is_prime[500001];

int main() {
	int n = ri();
	for (int i = 2; i <= 500000; i++) is_prime[i] = true;
	for (int i = 2; i <= 500000; i++) {
		if (!is_prime[i]) continue;
		for (int j = 2; j * i <= 500000; j++)
			is_prime[j * i] = false;
	}
	std::set<int64_t> primes;
	for (int i = 2; i <= n; i++) if (is_prime[i]) primes.insert(i);
	int res = 0;
	for (auto i : primes) {
		int64_t pow2 = (int64_t) i * i;
		if (pow2 > 2 * n) continue;
		for (auto j : primes) if (pow2 - j <= n && primes.count(pow2 - j)) res++;
	}
	std::cout << res << std::endl;
	
	return 0;
}