#include <iostream>
#include<fstream>
using namespace std;
int i,j,n,v[1000005];
long long tot;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>n;
    for(i=1;i<=n;i++) v[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=2*i;j<=n;j+=i)
         v[j]-=v[i];
    for(i=1;i<=n;i++)
        tot=1LL*tot+v[i];
    g<<2*tot+1;
    return 0;
}