#include<fstream>
using namespace std;
int v[1000001];
long long suma;
int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    int n;
    fin>>n;
    for(int i=1;i<=n;++i)
        v[i]=i-1;
    for(int i=2;i<=n;++i)
        for(int j=2*i;j<=n;j+=i)
            v[j]-=v[i];
    for(int i=1;i<=n;i++)
        suma+=v[i]*2;
    fout<<suma+1;
}