#include <iostream>
#include <math.h>
using namespace std;
int isP(int a)
{
	for(int j = 3;j <= sqrt(a);j+=2)
	if(!(a%j)) return a%j;
	return (a%a)+1;
}
int main() {
	int ans = 1;
	int n;
	cin >> n;
	if(n < 2)
	{
		cout << "0";
		return 0;
	}
	for(int i = 3;i*i <= n+1;i+=2)
	if(isP(i) && isP(i*i-2)) ans+=2;
	cout << ans;
	return 0;
}