#include <fstream>
#define NMAX 1000010
using namespace std;

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

int main()
{
    int n,x,i,v[NMAX],p=1,j;
    in>>n;
    for(i=1;i<=NMAX;i++)v[i]=i-1;
    for(i=2;i<=NMAX;i++)
        for(j=2*i;j<=NMAX;j=j+i) v[j]=v[j]-v[i];
    for(i=1;i<=NMAX;i++) p=p+v[i]*2;
    out<<p;
    in.close();
    out.close();
    return 0;
}