#include<iostream>
#include<vector>
#include<math.h>
using namespace std;

vector<int> prime;
int ans = 0;

int main(void) {
	void checkcount(int);
	int n,check=1;
	cin >> n;
	if (n < 2) {
		cout << 0;
		return 0;
	}
	prime.push_back(2);
		for (int i = 3; i <=n; i += 2) {
			check = 1;
			for (int j = 0; j < size(prime); j++) {
				if (i % prime[j] == 0) {
					check = 0;
					break;
				}
				if (prime[j] > sqrt(i)) break;
			}
			if (check) prime.push_back(i);
	    }
	for (int i = 0;i<size(prime); i++) {
		if (prime[i] * prime[i] > prime[size(prime) - 1]+2) break;
		checkcount(prime[i]);
	}

	cout << ans<<endl;
}

void checkcount(int r) {
	int left = -1, right = size(prime)-1,center;
	while (right - left != 1) {
		center = (left + right) / 2;
		if (prime[center] + 2 < r * r) left = center;
		else right = center;
	}
	if (prime[right] + 2 == r * r)
		ans += 1 + (prime[right] != 2);
}