#include<iostream>
#include<algorithm>
#include<vector>
#include <string>
#include<math.h>
#include<bitset>
typedef long long int ll;
using namespace std;
bool isprime(int n,int k=2){if(n==1){return false;}if(n<k*k){return true;}if(n%k==0){return false;}return isprime(n,k+1);}
int main(){
	ll n; cin >>n;
	int ans=0;
	if(n==1){
		cout <<0 << endl;
		return 0;
	}
	if(n==2){
		cout << 1 << endl;
		return 0;
	}
	for(int i=sqrtl(n);i>2;i--){
		if(isprime(i)){
			ll p=i*i;
			if(isprime(i*i-2)&&i*i-2<=n){
				ans+=2;
			}
		}
	}
	cout << ans+1 << endl;
}