#include <fstream>

using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main()
{

    long long k = 0;
    int n, i, j;
    fin>>n;
    for(i=2;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i+i;j<=n;j=j+i)
         {
            v[j]=v[j]-v[i];
         }
        k=k+v[i];
    }
    fout<<2*k+1;

    return 0;
}