#include <iostream>
#include <fstream>
#define nmax 1000000
using namespace std;

int P, N, Q, Pc, Qc, nr=0, i, j;
bool prim[nmax];

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f >> N;
    for(i=1; i<=N; i++) prim[i]=1;
    for(i=2; i<=N; i++)
    {
        if(prim[i])
        {
            for(j=2*i; j<=N; j+=i) prim[j] = 0;
        }

    }
    for(P=1; P<=N; P++)
    {
        for(Q=1; Q<=N; Q++)
        {
            if(P==1 || Q==1) nr++;
            else if(prim[P] == 1 && prim[Q] == 1) nr++;
        }
    }
g << nr;

    return 0;
}