#include <iostream>
#include <fstream>

using namespace std;
bool isPrime(int n){
	bool is = true;
	for(int m = 2; m<= n/2; m++){
	  if(n%m ==0)
		  is = false;
	} return is;}

int main(){
	ifstream in("fractii.in");
	ofstream out("fractii.out");
	int P,Q,N, nr = 0;
	in >> N;
	for(P = 1; P <= N; ++P){
	       for (Q = 1; Q <= N; ++Q){
	       		if (isPrime(P) && P !=2 ||  isPrime(Q) && Q!=2 )
	 			    nr++;}}

	out << --nr;
}