#include <iostream>
#include <math.h>
#include <map>
#include <vector>
using namespace std;
typedef long long LL;
int IsPrime (LL n)
{
    int i;
	if (n < 2){
        return 0;
	}
	if (n==2){
		return 1;
	}
	if (n % 2 == 0){
        return 0;
	}
	double sqrtNum = sqrt((double)n);
	for (i = 3; i <= sqrtNum; i += 2){
		if (n % i == 0 ){
            return 0;
		}
	}
    return 1;
}
int main(int argc, char* argv[])
{
	LL N,i,j;
	cin>>N;
	vector<LL> pri2;
	vector<LL> pri;
	LL I,J;
	I=0;
	for (i=1;i<=N;i++){
		if (IsPrime(i)==1){
			pri.push_back(i);
			if (I<=N){
				I=i*i;
				pri2.push_back(i*i);
			}
		}
	}
	int ans=0;
	int n1=pri.size();
	int n2=pri2.size();
	for (i=0;i<n2;i++){
		I=pri2[i];
		j=0;
		while (j<n1 &&pri[j]<=I){
			J=I-pri[j];
			if (IsPrime(J)==1){
				ans++;
			}
			j++;
		}
	}
	cout<<ans<<endl;
	return 0;
}