#include <fstream>

using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");

int phi[1000001];
int main()
{
int i,s=1,j,n;
in>>n;

for(i=1;i<=n;i++)
    phi[i]=i-1;

for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j=j+i)
            phi[j]=phi[j]-phi[i];

for(i=1;i<=n;i++)
    s=s+phi[i]*2;

out<<s;


    return 0;
}